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Refraction of seismic waves | Cosmology & Astronomy | Khan Academy

Video vocabulary

anything

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US / ˈeniθɪŋ /

UK / ˈɛniˌθɪŋ /

A1
  • pronoun
  • A thing of any kind

from

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US / frəm /

UK / frʌm, frɑm,frəm /

A1
  • preposition
  • Starting at a particular place, time or level

out

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US / aʊt /

UK / aʊt /

A1
  • adverb
  • No longer stylish (e.g. fashion)
  • Away from home, business, or the usual place
  • In a direction/movement away from inside or center
  • noun
  • Act when a batter cannot continue playing
  • verb
  • To tell people a secret

over

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US / 'əʊvə(r) /

UK / ˈovɚ /

A1
  • adverb
  • Finished; no longer happening
  • Towards the ground/away from a standing position
  • noun
  • A set of six consecutive balls bowled in cricket
  • other
  • Finished
  • preposition
  • Showing the relation when a thing is above another
  • On or covering something
  • Above or across something
  • More than you need
  • From one side to the other
  • In the direction of; toward

any

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US / 'enɪ /

UK / ˈɛni /

A1
  • adjecitve
  • One, or some, no matter which
  • pronoun
  • One (thing) of many; some

come

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US / kʌm /

UK / kʌm /

A1
  • verb
  • To arrive at a place
  • (Of mail) to be delivered
  • To move toward someone; go with someone
  • To reach a certain point or state

composition

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US / ˌkɒmpəˈzɪʃn /

UK / ˌkɑ:mpəˈzɪʃn /

A2
  • noun
  • Piece of writing, music etc.
  • A piece of music
  • Structure of a picture or image to make an effect

experiment

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US / ɪk'sperɪmənt /

UK / ɪkˈspɛrəmənt /

A2
  • noun
  • Test performed to assess new ideas or theories
  • verb
  • To create and perform tests to research something
  • To try something new that you haven't tried before

help

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US / help /

UK / hɛlp /

A1
  • noun
  • Something given to enable a person to do something
  • Assistance given to someone in need
  • Someone who makes something easier or possible
  • verb
  • To act to enable a person to do something; assist
  • To make something better or less difficult

layer

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US / ˈleiə /

UK / ˈleɚ /

B1
  • noun
  • One of several sheets of a material or object
  • verb
  • To put things one on top of another

literally

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US / ˈlɪtərəli /

UK / ˈlɪtərəli /

B1
  • adverb
  • So as to express the exact meaning of something
  • Used to say something is true, even if unlikely

observe

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US / əbˈzɜ:v /

UK / əbˈzɜ:rv /

A2
  • verb
  • To celebrate a particular holiday/religious event
  • To obey or follow laws, rules, or customs
  • To watch carefully; to make a comment

wave

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US / weɪv /

UK / wev /

A2
  • noun
  • Movement of sound, air or energy
  • Deep and strong emotion that is suddenly felt
  • Slightly curved shape in hair
  • Frequency of movement of objects together
  • Up and down movement of water in a lake or sea
  • Signal with your hand to say hello or goodbye
  • verb
  • To cause to move side to side or back and forth
  • To swing back and forth as a result of the wind
  • To move your hand or arm to say hello or goodbye

think

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US / θɪŋk /

UK / θɪŋk /

A1
  • verb
  • To have an idea about something without certainty
  • To have an idea, opinion or belief about something

another

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US / əˈnʌðə(r) /

UK / əˈnʌðɚ /

A1
  • adjecitve
  • One more, but not this
  • determiner
  • One more added
  • pronoun
  • One more (thing)

approximation

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US / əˌprɒksɪˈmeɪʃn /

UK / əˌprɑksəˈmeʃən /

B2
  • noun
  • Something that is similar, but not an exact copy

continuous

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US / kənˈtɪnjuəs /

UK / kənˈtɪnjuəs /

A2
  • adjecitve
  • Happening, existing, or performed without stops

something

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US / ˈsʌmθɪŋ /

UK / ˈsʌmθɪŋ /

A1
  • adverb
  • In some degree or measure
  • noun
  • a person or thing of some value or consequence
  • pronoun
  • Thing that is not yet known or named
  • Approximately

and

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US / ənd /

UK / ənd, ən,ænd /

A1
  • conjunction
  • Used to refer to two or more things
  • Plus; in addition; on top of that
  • Used to introduce an action that follows another

back

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US / bæk /

UK / bæk /

A1
  • adjecitve
  • Farthest from the front e.g. in a classroom
  • adverb
  • Have returned to a place you were before
  • noun
  • The part of a chair that the upper body leans upon
  • Location at the rear of something
  • The reverse of side something
  • Area on the rear of your body
  • verb
  • To bet money on something
  • To go backwards in a car
  • To support and encourage someone or some cause

base

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US / beɪs /

UK / bes /

A2
  • noun
  • Place military personnel live, train, and operate
  • Bottom part of an object that touches a surface
  • Unit of counting, e.g. 10 for counting
  • Most important idea or ingredient to add others
  • Origin or start from which something came
  • Main place where an organization or a person works
  • verb
  • To use as the starting point or origin for
  • To have as the main location for (company, etc.)

guy

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US / ɡaɪ /

UK / ɡaɪ /

A1
  • noun
  • Man; boy; any person

hopefully

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US / ˈhəʊpfəli /

UK / ˈhopfəli /

A2
  • adverb
  • In a manner wishing something to happen

most

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US / məʊst /

UK / most /

A1
  • adverb
  • Very; extremely
  • Greatest possible degree
  • pronoun
  • Nearly all of something

far

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US / fɑ:(r) /

UK / fɑr /

A1
  • adjecitve
  • A long way away
  • Being a long way away
  • adverb
  • To a large degree or extent

leave

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US / li:v /

UK / liv /

A1
  • noun
  • Permission to do something
  • Vacation time; time off work
  • verb
  • To go away from; depart
  • To gift property to someone after you die
  • To allow something to continue happening
  • To let something remain unused or available
  • To let something or someone remain somewhere

where

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US / hwɛə /

UK / hwɛr, wɛr /

A1
  • conjunction
  • At or in the place which
  • In whatever place
  • pronoun
  • Word you use to ask the location of something

completely

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US / kəmˈpli:tli /

UK / kəmˈpliːtli /

A1
  • adverb
  • In every way or as much as possible

continue

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US / kən'tɪnju: /

UK / kənˈtɪnju /

A1
  • verb
  • To do something without stopping, or after pausing
  • To start doing again after a break, pause, or stop

reflection

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US / rɪˈflekʃn /

UK / rɪˈflɛkʃən /

A2
  • noun
  • Sign or indication of a state or condition
  • Image that you see in a mirror, glass, or water
  • An image in glass, water, a mirror, etc.
  • Process of thinking carefully about something

shallow

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US / 'ʃæləʊ /

UK / ˈʃælo /

B1
  • adjecitve
  • Not deep; short from top to bottom
  • Lacking interest in serious things; superficial

should

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US / ʃʊd /

UK / ʃʊd /

A1
  • other
  • Used to indicate what is proper or reasonable

side

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US / saɪd /

UK / saɪd /

A1
  • adjecitve
  • In addition to the central or most important thing
  • Next to, or very close to, the right or left of
  • noun
  • Position or opinion that is opposite to another
  • Right or left part of a person's body
  • Feature of someone's personality
  • Straight edge of an object
  • One of two or more groups fighting each other
  • verb
  • To decide to agree with one point, not the other

wheel

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US / wi:l /

UK / wi:l /

A2
  • noun
  • Round thing that rolls, used for moving things
  • verb
  • To move something which has wheels or is on wheels
  • To turn or cause to turn something in a circle

billiard

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US / 'bɪlɪəd /

UK / 'bɪlɪrd /

C1
  • adjecitve
  • Game to put balls in nets at corners of a table

compress

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US / kəmˈpres /

UK / kəmˈprɛs /

B1
  • verb
  • To press tightly together
  • To make smaller; reduce in time, size etc.

here

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US / hɪə(r) /

UK / hɪr /

A1
  • adverb
  • In this place; at this location, position or time

quick

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US / kwɪk /

UK / kwɪk /

A1
  • adjecitve
  • Using very little time; moving far in little time
  • Learning and understanding rapidly and easily

stuck

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US / stʌk /

UK / stʌk /

A2
  • adjecitve
  • Not able to move
  • verb
  • To push a sharp or pointed object into something
  • To join together using glue or paste
  • To remain in one place or position for a long time

try

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US / traɪ /

UK / traɪ /

A1
  • noun
  • Act of putting the ball over the rugby goal line
  • verb
  • To make an effort, to attempt to do something
  • To examine someone or something in a court of law
  • To test to see if it is good or you like it
  • To make a person go through hardship; test
  • To examine something to see if it works

actually

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US / ˈæktʃuəli /

UK / ˈæktʃuəli /

A1
  • adverb
  • Used to add new (often different) information

use

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US / ju:s /

UK / ju:s /

A1
  • noun
  • Ability to employ something
  • Need to enable it to work
  • Permission to do something with something
  • Act of spending money
  • Operation of a machine for its function
  • verb
  • To have; to eat, drink, consume etc.
  • To need to operate or work
  • To operate a machine, e.g. a computer
  • To treat a person badly
  • To do something with, for a task or purpose

uniform

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US / ˈju:nɪfɔ:m /

UK / ˈju:nɪfɔ:rm /

A2
  • adjecitve
  • Not changing your conduct or opinion
  • noun
  • Set of clothes showing you belong to an army, etc.
  • verb
  • To dress in formal clothes like the army wear
  • To make a group of things the same

straight

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US / streɪt /

UK / stret /

A2
  • adjecitve
  • Not having curves, bends, or angles
  • Not gay; heterosexual
  • honest and direct
  • adverb
  • in a line; immediately; honestly and directly

intuitive

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US / ɪnˈtju:ɪtɪv /

UK / ɪnˈtuɪtɪv, -ˈtju- /

B2
  • adjecitve
  • Able to understand by feeling rather than fact

liquid

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US / ˈlɪkwɪd /

UK / ˈlɪkwɪd /

A2
  • adjecitve
  • (Of wealth) being able to be spent as cash
  • In a state of being uncertain
  • Moving in a flowing manner, like water or oil
  • noun
  • Something that is similar to the state of water

will

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US / wɪl /

UK / wɪl /

A1
  • noun
  • Desire or choice of someone
  • Document saying who gets your money when you die
  • Strong desire to do something; determination
  • Desire to do something; strong wish to do
  • other
  • Used with verbs to express the future
  • verb
  • To leave property to someone after your death
  • To use mental effort to make something happen
  • Am (is, are) likely to do
  • To influence someone to do something
  • To make something happen by strongly wanting it

imagine

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US / ɪ'mædʒɪn /

UK / ɪˈmædʒɪn /

A1
  • verb
  • To think creatively about; form mental picture of

obviously

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US / ˈɒbviəsli /

UK / ˈɑːbviəsli /

A2
  • adverb
  • In a way that is obvious/easy to see or understand

once

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US / wʌns /

UK / wʌns /

A1
  • adverb
  • One time; one instance
  • At a time in the past
  • conjunction
  • When; as soon as

clear

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US / klɪə(r) /

UK / klɪr /

A1
  • adjecitve
  • Empty; without anything in it or on it
  • Being certain and without doubt
  • Being without any streaks, spots, or cracks
  • Easy to understand; well-explained; obvious
  • adverb
  • Completely; entirely; through the whole of
  • Away from; free from
  • verb
  • To recover from or remove a problem
  • To get rid of the entire contents of
  • To give permission for something to happen
  • To make a place or surface empty by removing
  • To prove that someone is not guilty or to blame

next

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US / nekst /

UK / nɛkst /

A1
  • adverb
  • The one that follows another in time or order
  • At a time or place directly after the present one
  • noun
  • The one that follows after
  • adjecitve
  • Immediately after the previous one
  • First occurrence after the present one

draw

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US / drɔ: /

UK / drɔ /

A1
  • noun
  • Something that attracts people to visit a place
  • A lottery or prize
  • Result of a game, contest where the score is equal
  • verb
  • To attract attention to someone or something
  • To get closer to or approach something or someone
  • To influence a person's involvement in something
  • To move an object by pulling
  • To create an image using pen or pencil and paper
  • To take one thing out of a container, etc.
  • (Of 2 teams) to finish a game with the same score

increase

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US / ɪn'kri:s /

UK / ɪnˈkris /

A1
  • noun
  • Fact of increasing; amount something grows by
  • verb
  • To make or become larger in size or amount

before

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US / bɪˈfɔ:(r) /

UK / bɪˈfɔr,-ˈfor /

A1
  • adverb
  • At a time earlier than the present; previously
  • conjunction
  • In advance of something happening
  • preposition
  • In front of someone or something

information

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US / ˌɪnfəˈmeɪʃn /

UK / ˌɪnfɚˈmeʃən /

A1
  • noun
  • Collection of facts and details about something

have

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US / həv /

UK / hæv /

A1
  • verb
  • To drink, smoke, eat or use something
  • To experience the effects of something
  • To organize an event, or join in an activity
  • To own, possess, or hold something
  • To cause to happen or produce a particular effect

rebound

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US / rɪ'baʊnd /

UK / ˈriˈbaʊnd, rɪ- /

B2
  • noun
  • Bouncing off something, then going back into play
  • Recovery after defeat/bad time back to good state
  • verb
  • To bounce off of a surface
  • To recover or increase after decreasing

with

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US / wɪð /

UK / wɪð, wɪθ /

A1
  • preposition
  • As an employee of a certain company
  • Against something or someone
  • By using something as a means
  • Due to; because of
  • Including
  • Possessing as a feature
  • Related to
  • (Of the manner/attitude by which you do something)
  • Used to express that people or things are together

could

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US / kəd /

UK / kʊd /

A1
  • other
  • Past form of 'can' to mean have ability
  • Used to ask for something politely, or to offer

know

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US / nəʊ /

UK / noʊ /

A1
  • verb
  • To be familiar with a person or place, thing
  • To feel sure or be convinced about something
  • To discover or be aware of something
  • To be able to distinguish
  • To have knowledge of things

slightly

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US / ˈslaɪtli /

UK / ˈslaɪtli /

B1
  • adverb
  • Only a little

bent

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US / bent /

UK / bɛnt /

A2
  • adjecitve
  • Become curved or no longer straight
  • verb
  • To become curved or no longer straight
  • To move your body so that it is not straight up
  • To turn in a different direction, as a road
  • To use force to make an object not straight

crust

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US / krʌst /

UK / krʌst /

B2
  • noun
  • Hard outer layer of something, e.g. the earth
  • Hard crisp outer layer of bread, baked goods

car

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US / kɑ:(r) /

UK / kɑr /

A1
  • noun
  • A vehicle with wheels and engine to carry people

see

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US / si: /

UK / si /

A1
  • verb
  • To go on a date with someone
  • To predict whether something is, or will be true
  • To understand what someone says
  • To use your eyes to look at something
  • To visit a place often for sightseeing or pleasure
  • To visit or meet with someone
  • To find out by waiting or looking
  • To watch (a game, movie or TV show)

center

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US / 'sentə /

UK / ˈsɛntɚ /

A1
  • noun
  • Community place people go health or social reasons
  • Place in the middle of something
  • Person or thing that is attracting attention
  • verb
  • To direct focus toward something

focus

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US / 'fəʊkəs /

UK / ˈfokəs /

A2
  • noun
  • Main purpose or center of interest or activity
  • verb
  • To see clearly by adjusting your eyes or a camera
  • To keep your attention, concentration on one thing

less

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US / les /

UK / lɛs /

A1
  • adjecitve
  • Smaller in amount or degree
  • adverb
  • To a smaller degree
  • noun
  • A smaller amount
  • preposition
  • With the subtraction of

tire

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US / ˈtaɪə(r) /

UK / taɪr /

B1
  • noun
  • Black rubber part of wheels on a vehicle
  • The rubber rings around wheels on cars and trucks
  • verb
  • To lose, cause to lose energy so you want to rest

let

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US / let /

UK / lɛt /

A1
  • verb
  • To allow someone to do something
  • Introducing a suggestion to do something together
  • To rent a house, etc. to others

material

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US / məˈtɪəriəl /

UK / məˈtɪriəl /

A2
  • adjecitve
  • Relevant; (of evidence) important or significant
  • Belonging to the world of physical things
  • noun
  • Cloth; fabric
  • Supplies or data needed to do a certain thing
  • Substance from which a thing is made of

little

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US / 'lɪtl /

UK / ˈlɪtl /

A1
  • adjecitve
  • Being short in length of time
  • Not great in size, amount, or degree; small
  • Being very young or younger than others
  • adverb
  • By an amount or degree that is not very much
  • Not often; rarely
  • noun
  • A person's name

molecular

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US / mə'lekjələ(r) /

UK / məˈlɛkjəlɚ /

B2
  • adjecitve
  • About or caused by molecules

the

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US / ðə /

UK / ðə /

A1
  • article
  • Used to refer to something already mentioned
  • Used to show there is only one of something
  • determiner
  • Used to describe all of a family

this

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US / ðɪs /

UK / ðɪs /

A1
  • adjecitve
  • Used to indicate something already been discussed
  • Used to indicate something happening around now
  • adverb
  • An indication by a physical motion or gesture
  • A specific amount of
  • determiner
  • Person, thing, or idea near you
  • pronoun
  • Person, thing that has already been discussed

able

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US / 'eɪbl /

UK / ˈebəl /

A2
  • adjecitve
  • Skilled; good at something
  • Having the ability to do something

term

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US / tɜ:m /

UK / tɚm /

A1
  • noun
  • Conditions applying to an agreement, contract
  • Length of time something is expected to happen
  • Fixed period of weeks for learning at school
  • The (precise) name given to something
  • verb
  • To call; give a name to

surface

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US / 'sɜ:fɪs /

UK / ˈsɚfəs /

A2
  • adjecitve
  • Of the top layer; not deep or meaningful
  • noun
  • Top layer of the ground or of water
  • Nature or emotions that show, but may not be true
  • Outside or upper layer of something
  • verb
  • To give (road) a top layer
  • To appear after being hidden, unseen, or unknown
  • To come to the top of something; emerge
  • To come to the top level of water, mud, etc.

how

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US / haʊ /

UK / haʊ /

A1
  • adjecitve
  • To what degree? in what amount?
  • adverb
  • (Used to explain the way to do something)
  • exclamation
  • For what purpose or reason?
  • (Used to ask someone or something's condition)

kind

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US / kaɪnd /

UK / kaɪnd /

A1
  • adjecitve
  • In a caring and helpful manner
  • friendly and considerate
  • noun
  • One type of thing

you

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US / jʊ /

UK / ju /

A1
  • pronoun
  • Person someone is speaking or writing to
  • Person or people in general

earthquake

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US / ˈɜ:θkweɪk /

UK / ˈɜ:rθkweɪk /

B1
  • noun
  • Heavy shaking of the ground due to natural forces

into

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US / 'ɪntə /

UK / ˈɪntu /

A1
  • preposition
  • Moving or going inside something
  • In the same direction as; in the direction of
  • So as to become; taking the state of

forward

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US / 'fɔ:wəd /

UK / ˈfɔrwəd /

A1
  • adjecitve
  • Toward what is ahead; in front
  • Acting in a socially aggressive manner; pushy
  • adverb
  • Toward the front in place; in front
  • Toward a future time; to a more advanced state
  • verb
  • To send something to another address or person

one

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US / wʌn /

UK / wʌn /

A1
  • pronoun
  • You; we; people in general; someone
  • The thing or person previously referred to
  • adjecitve
  • Used to refer to people generally
  • Being a strong example of (something mentioned)
  • number
  • Number 1

other

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US / 'ʌðə(r) /

UK / ˈʌðər /

A1
  • adjecitve
  • A thing different from that mentioned
  • determiner
  • (Something) else; not the first (one)
  • pronoun
  • Being the one and only thing of that category

rock

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US / rɒk /

UK / rɑk /

A1
  • noun
  • Type of popular music with a strong, loud beat
  • Strong, tough person who can be relied upon
  • Big stone; hard, solid substance forming mountains
  • verb
  • To be greatly upset by something, e.g. a death
  • To be extremely effective or pleasing
  • To play, sing along with, or dance to heavy music
  • To move back and forth or from side to side

turn

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US / tɜ:n /

UK / tɚn /

A1
  • noun
  • Place where changing of direction happens
  • Your time or chance to perform a duty
  • Your chance to play or do in say a game
  • Unexpected change, as in the weather
  • verb
  • To become (a particular age)
  • To become a different quality, color, etc.
  • To change the direction of something, e.g. a car
  • To move in an opposite direction or position
  • To shape metal with a spinning tool

than

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US / ðən /

UK / ðən /

A1
  • conjunction
  • Used to compare two things that are not equal

deep

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US / di:p /

UK / dip /

A1
  • adjecitve
  • Complex and important
  • Extreme or intense
  • Going far down from the surface
  • Low in pitch, as a sound
  • adverb
  • At a certain distance beneath the surface

level

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US / 'levl /

UK / ˈlɛvəl /

A2
  • adjecitve
  • (Sports) equal to another
  • Being steady and determined (e.g. a voice)
  • noun
  • Specific height of something
  • Amount of ability you have compared to others
  • Floor or deck within a building
  • Tool used to determine if something is lying flat
  • verb
  • To aim a gun at someone
  • To destroy a building; flatten an area completely
  • To make things flat or even
  • To make a score equal to another, in sports

below

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US / bɪ'ləʊ /

UK / bɪˈlo /

A1
  • preposition
  • In a lower position, place, or level

make

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US / meɪk /

UK / mek /

A1
  • noun
  • Product made by a particular company; brand
  • verb
  • To arrange or prepare something e.g. dinner
  • To get to (a place) on time
  • To gain the status of (teacher, lawyer, etc.)
  • To create something by putting things together
  • To earn a certain amount of money at a job
  • To cause or force a person to do something
  • To cause something to happen or be formed

ones

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US / wʌnz /

UK / wʌnz /

A1
  • number
  • Number 1, a single person or thing

bump

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US / bʌmp /

UK / bʌmp /

B1
  • noun
  • Act or sound of one solid object hitting another
  • Raised area on any smooth surface
  • verb
  • To bounce along over a rough surface
  • To knock against with force or violence
  • To move someone to a different group, time or area

curve

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US / kə:v /

UK / kɚv /

A2
  • noun
  • Smooth rounded line that is not straight
  • verb
  • To make something bend into a rounded shape

principle

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US / ˈprɪnsəpl /

UK / ˈprɪnsəpəl /

A2
  • noun
  • Moral rule or belief governing a person's behavior
  • Natural law that explains how things work

they

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US / ðeɪ /

UK / ðe /

A1
  • pronoun
  • Two or more people, animals, or things

all

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US / ɔ:l /

UK / ɔl /

A1
  • adverb
  • Completely; totally
  • determiner
  • Being every one of something
  • pronoun
  • 100% of something; the complete amount

fast

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US / fɑ:st /

UK / fæst /

A1
  • adjecitve
  • In a way that is difficult to move or change
  • Moving or able to move quickly
  • Showing time that is later than the actual time
  • adverb
  • With a great deal of speed
  • noun
  • Period of time when a person chooses not to eat
  • verb
  • To refuse food for a long time

its

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US / ɪts /

UK / ɪts /

A1
  • adjecitve
  • Referring to or belonging to ‘it’
  • determiner
  • Of something; belonging or related to something
  • other
  • Possessive form of “it”

seismic

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US / ˈsaɪzmɪk /

UK / ˈsaɪzmɪk /

B2
  • adjecitve
  • Of earthquakes

top

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US / tɒp /

UK / tɑp /

A1
  • adjecitve
  • Being good or great; excellent
  • Being the most in degree or quality
  • noun
  • Item of clothing covering shoulders to waist, hips
  • A cover or lid
  • Part (e.g. road) that is the furthest away
  • Highest or upper part or point of something
  • Best or highest status or position
  • Flat upper surface or edge of an object
  • Child's toy that spins on its point
  • Upper section or leaves of fruits and vegetables
  • Winning in a sport or contest
  • verb
  • To be higher or larger than a specific value
  • To arrive at the highest point of something
  • To put a cover or layer or over something
  • To kill; murder
  • To hold the highest position on a list
  • To be more important, successful or better than
  • To beat someone or win at a game

bit

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US / bɪt /

UK / bɪt /

A1
  • noun
  • Device put in a horse's mouth to control it
  • Small piece of something
  • verb
  • (E.g. of fish) to take bait and be caught

general

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US / 'dʒenrəl /

UK / ˈdʒɛnərəl /

A1
  • adjecitve
  • Widespread, normal or usual
  • noun
  • Top ranked officer in the army

look

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US / lʊk /

UK / lʊk /

A1
  • noun
  • Person's beauty or physical attractiveness
  • Particular style of dress, clothes, or appearance
  • The way someone, something appears to be
  • Act of searching for or examining something
  • verb
  • To appear to be; seem

bounce

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US / baʊns /

UK / baʊns /

B1
  • noun
  • A person's energy or confidence
  • Quality causing a person's hair to appear healthy
  • verb
  • To move around energetically, playfully
  • To forcibly remove a person from a bar, nightclub
  • (Of check) to be rejected due to inadequate funds
  • To strike a surface and rapidly change direction
  • To move energetically in an up and down motion

figure

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US / ˈfiɡə /

UK / ˈfɪɡjɚ /

A1
  • noun
  • Your body shape
  • Numbers in a calculation
  • Doll-like thing meant to represent a person
  • Picture or diagram giving information in a text
  • Person who is very important or famous
  • Shape of a person seen indistinctly or in outline
  • Amount that is expressed in numbers
  • verb
  • To appear in a game, play or event
  • To calculate how much something will cost
  • To understand after thinking; work out

direction

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US / də'rekʃn /

UK / dɪˈrɛkʃən, daɪ- /

A2
  • noun
  • When someone tells people what to do
  • Describes the way you are going, e.g. North

move

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US / mu:v /

UK / muv /

A1
  • noun
  • Act of moving a playing piece in chess, etc.
  • An action; doing something
  • Step taken to achieve a goal
  • verb
  • To cause someone to have certain emotions
  • To cause something to change to a different place
  • To change where people live or a business operates
  • To take action to do or achieve something

way

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US / weɪ /

UK / we /

A1
  • adverb
  • Used to emphasize the amount of something
  • noun
  • Particular aspect of something being thought about
  • One of various choices that could be made
  • Particular existing condition or state
  • (Often long) distance or length of time
  • How something is done
  • Route to go to a place
  • Small street
  • Usual behavior, emotions or habits of someone

approach

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US / ə'prəʊtʃ /

UK / əˈprəʊtʃ /

A2
  • noun
  • Means of reaching a place, often a road or path
  • Request of someone with a specific goal in mind
  • Specific way to handle a project, task, problem
  • verb
  • To get close to reaching something or somewhere
  • To request someone to do something specific

both

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US / bəuθ /

UK / boθ /

A1
  • determiner
  • Used to refer to two things at the same time
  • pronoun
  • Used to refer to two things at the same time

change

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US / tʃeɪndʒ /

UK / tʃendʒ /

A1
  • noun
  • Exchange of one set of clothes for another
  • Money in the form of coins instead of paper
  • Money returned after giving too much
  • Act of making or becoming something else
  • verb
  • To exchange one set of clothes for another
  • To exchange one kind of money for another
  • To replace something with another thing
  • To make or become something else
  • To go from one train, bus, etc. and go to another

pressure

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US / 'preʃə(r) /

UK / ˈprɛʃɚ /

A2
  • noun
  • Anxiety caused by difficult problems
  • Force, weight when pressing against a thing
  • Strong persuasion to do something
  • verb
  • To apply force to something
  • To persuade or force someone to do something

simple

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US / 'sɪmpl /

UK / ˈsɪmpəl /

A1
  • adjecitve
  • Not hard to understand or do; not complex
  • Having only a few parts; not complex
  • Being ordinary or normal
  • Being plain; without a lot added for style

travel

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US / ˈtrævl /

UK / ˈtrævəl /

A1
  • noun
  • Going to other places, esp. distant places
  • verb
  • To go to a place that is far away

clearly

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US / ˈklɪəlɪ /

UK / ˈklɪrlɪ /

A1
  • adverb
  • In a way that is easy to understand; obviously

constantly

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US / ˈkɒnstəntli /

UK / ˈkɑnstəntlɪ /

B1
  • adverb
  • Frequently, or without pause

dense

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US / dens /

UK / dɛns /

B1
  • adjecitve
  • Very thick and difficult to see, get through
  • Hard to understand
  • Uncomprehending; foolish; inconsiderate

confusing

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US / kənˈfju:zɪŋ /

UK / kənˈfjuzɪŋ /

A2
  • adjecitve
  • Being hard to understand
  • verb
  • To make something unclear or hard to understand

pretty

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US / 'prɪtɪ /

UK / ˈprɪti /

A1
  • adjecitve
  • Being attractive to the eye in a simple way
  • adverb
  • Very; to a great degree

analogous

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US / əˈnæləgəs /

UK / əˈnæləɡəs /

B2
  • adjecitve
  • Similar and comparable to

slight

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US / slaɪt /

UK / slaɪt /

B1
  • adjecitve
  • Small (amount, quality)
  • Appearing thin, delicate and physically weak
  • noun
  • Rude and disrepectful treatment
  • verb
  • To ignore or treat rudely and with no respect

again

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US / ə'ɡen /

UK / əˈɡɛn /

A1
  • adverb
  • One more time, once more

about

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US / ə'baʊt /

UK / əˈbaʊt /

A1
  • adverb
  • To be ready to; going to
  • Nearly; approximately; roughly
  • Near; next to; close to
  • In every direction; in the area of
  • preposition
  • Concerning or of (a topic)

even

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US / 'i:vn /

UK / ˈivən /

A1
  • adjecitve
  • Being equal in influence, power, possibility etc.
  • Being divided equally or fairly
  • (Of teams/contest) with similar chances of success
  • Smooth, level, or regular
  • Can be divided by 2; ending in 2, 4, 6, 8, or 0
  • At a regular, equally steady manner
  • Remaining steady and unchanging
  • adverb
  • (When this is surprising) as well; too
  • (Used to compare two things/stress the difference)
  • verb
  • To make something level; to flatten
  • To make something equal

different

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US / ˈdɪfrənt /

UK / ˈdɪfrənt /

A1
  • adjecitve
  • Not of the same kind; unlike other things

like

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US / laɪk /

UK / laɪk /

A1
  • adjecitve
  • Being equal in status or kind to something else
  • Similar; the same
  • adverb
  • For example
  • preposition
  • Used as a filler; used to ad emphasis
  • In a way similar to the way something is done
  • Such as; for example
  • verb
  • To want to
  • To find something pleasing; to prefer something

reaction

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US / rɪ'ækʃn /

UK / riˈækʃən /

A2
  • noun
  • Bodily response to a drug or something eaten
  • Feeling or action in response to something

what

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US / wɒt /

UK / hwɑt, hwʌt, wɔt, wʌt,hwət, wət /

A1
  • pronoun
  • Thing or things that; the same kind as
  • Used to emphasize something you are about to say
  • adjecitve
  • Used to refer to a particular amount, or number
  • Used to place emphasis on a particular quality
  • adverb
  • To a certain degree
  • determiner
  • Question words used for asking for information
  • exclamation
  • Used to express excitement, shock, or surprise
  • Used to ask people to repeat something they said

that

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US / ðæt /

UK / ðæt, ðət /

A1
  • adjecitve
  • The person or thing being talked about
  • Used to identify something both the speakers know
  • adverb
  • Used to reinforce adjectives and adverbs
  • To such a degree
  • conjunction
  • Used to connect a noun clause
  • Used to introduce an adverbial clause
  • Used to introduce a noun clause
  • determiner
  • Used as a noun to refer to something
  • pronoun
  • Referring an object far away
  • Used to refer to the relative pronoun ‘which’

first

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US / fɜ:st /

UK / fɚst /

A1
  • adjecitve
  • 1st; Coming before all others in time or place
  • noun
  • Something that has not happened before
  • Position of the winner of a competition

get

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US / ɡet /

UK / ɡɛt /

A1
  • verb
  • To become affected by illness or disease
  • To begin to feel or understand an emotion or idea
  • To send or bring someone or something home, etc.
  • To go somewhere to obtain something
  • To (cause to) do a particular thing
  • To obtain, receive or be given something
  • To currently have
  • To prepare for use
  • To understand something being said or read

medium

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US / 'mi:dɪəm /

UK / ˈmidiəm /

A2
  • noun
  • Method of expressing ideas or feelings
  • Something available in a middle size or condition
  • Person who claims to communicate with the dead

traction

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US / ˈtrækʃn /

UK / ˈtrækʃən /

C1
  • noun
  • Force causing moving thing to stick, e.g. on roads

dismiss

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US / dɪsˈmɪs /

UK / dɪsˈmɪs /

A2
  • verb
  • To consider that something is at an end
  • To end someone's employment; fire someone
  • To not to think about something seriously

down

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US / daʊn /

UK / daʊn /

A1
  • adjecitve
  • Being sad, sick, or unhappy
  • Not operating, working, or functioning as expected
  • adverb
  • In a sitting or lying position
  • Towards or on the ground, floor, or bottom
  • Written or copied onto a piece of paper or book
  • noun
  • A period of play in American Football
  • The soft, smooth hairs that cover a bird's body
  • preposition
  • Along something's path, course, or direction
  • Going from a higher position to a lower position
  • verb
  • To eat or drink very quickly and without stopping

slowly

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US / ˈsləʊli /

UK / ˈsloʊli /

A1
  • adverb
  • In an unhurried or not speedy manner

then

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US / ðen /

UK / ðɛn /

A1
  • adverb
  • A time that is not now
  • Following another thing in time or arrangement
  • Following on reasonably from what was just stated
  • At that time, not now

boundary

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US / 'baʊndrɪ /

UK / ˈbaʊndəri, -dri /

B1
  • noun
  • A division or border to separate two areas

case

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US / keɪs /

UK / kes /

A1
  • noun
  • Container used to carry things, e.g. clothes
  • Set of facts about a crime
  • Set of facts about an event
  • Example or instance of something
  • verb
  • To find out about a place, as in planning to steal

deflect

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US / dɪ'flekt /

UK / dɪˈflɛkt /

B2
  • verb
  • To cause to turn in a different direction
  • To prevent or avoid something having an effect on

discrete

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US / dɪˈskri:t /

UK / dɪˈskrit /

B2
  • adjecitve
  • Separate; composed of distinct parts

type

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US / taɪp /

UK / taɪp /

A1
  • noun
  • Printed letters or blocks used for printing them
  • Group of things or people sharing common features
  • verb
  • To identify something belonging to a group
  • To write by touching keys on a keyboard

ball

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US / bɔ:l /

UK / bɔl /

A1
  • noun
  • Large dance where people dress formally
  • Small round object often used in a game or sport

essentially

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US / ɪˈsenʃəli /

UK / ɪˈsenʃəli /

A2
  • adverb
  • Basically; (said when stating the basic facts)

least

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US / li:st /

UK / list /

A1
  • adverb
  • In the smallest or lowest way
  • noun
  • Something that is of the lowest or smallest degree

primer

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US / 'praɪmə(r) /

UK / ˈprɪmɚ /

B2
  • noun
  • A kind of paint put on to make the top coat better
  • A book that covers the basics of a subject

right

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US / raɪt /

UK / raɪt /

A1
  • adjecitve
  • Correct or true
  • The south side of you looking at the rising sun
  • adverb
  • Exactly in a place or time
  • Being appropriate for a particular event
  • In a straight or direct manner
  • noun
  • Something you are legally or morally allowed to do
  • Ideal of what is just and good
  • Political view based on conservatism
  • verb
  • To fix something previously wrong or unjust
  • To make upright, as a boat that has turned over

hit

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US / hɪt /

UK / hɪt /

A1
  • noun
  • A planned killing, usually for money
  • Song, movie etc. that is successful
  • When someone strikes someone or something
  • Time when a player makes contact with the ball
  • Time when a website is accessed
  • verb
  • To have a negative impact on a person/place/thing
  • To press something, such as a button or switch
  • To suddenly realize the importance of something
  • To move your hand, a bat, etc. against with force
  • To fight, attack or damage something or someone
  • To arrive at a specific place, level, or goal
  • To make contact with the ball in a game or sport

nothing

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US / 'nʌθɪŋ /

UK / ˈnʌθɪŋ /

A1
  • noun
  • Item of little or no value, importance, interest
  • Number or value of zero
  • pronoun
  • Not anything, not a single thing

accentuate

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US / ək'sentʃʊeɪt /

UK / ækˈsɛntʃuˌet /

B2
  • verb
  • To emphasize a difference; make more noticeable

bottom

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US / 'bɒtəm /

UK / ˈbɑtəm /

A2
  • adjecitve
  • Concerning the part under something, e.g. a vase
  • noun
  • The part of your body you sit on
  • Lowest position, often in a company or contest
  • Lowest part of something; part on which it rests
  • Lowest level, part or point of an object
  • The part under something, e.g. a vase
  • verb
  • To hit the lowest part of something

closely

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US / 'kləʊslɪ /

UK / ˈkloslɪ /

A2
  • adverb
  • In a careful manner
  • Nearby; just next to

each

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US / i:tʃ /

UK / itʃ /

A1
  • determiner
  • Every one of two or more things
  • pronoun
  • Per one person or thing

example

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US / ɪgˈzɑ:mpl /

UK / ɪɡˈzæmpəl /

A1
  • noun
  • Thing, person which represents a category

inform

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US / ɪnˈfɔ:m /

UK / ɪnˈfɔ:rm /

A2
  • verb
  • To give information or facts about something

happen

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US / 'hæpən /

UK / ˈhæpən /

A1
  • verb
  • To take place or occur

reminder

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US / rɪˈmaɪndə(r) /

UK / rɪˈmaɪndər /

A2
  • noun
  • Something that causes one to remember something

time

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US / taɪm /

UK / taɪm /

A1
  • noun
  • Speed at which music is played; tempo
  • Point as shown on a clock, e.g. 3 p.m
  • Number of hours, minutes needed to do something
  • Occasion when something happens
  • Period or occasion that something occurred
  • Period in history or the past
  • Something measured in minutes, hours, days, etc.
  • How long an event takes; duration
  • verb
  • To check speed at which music is performed
  • To choose a specific moment to do something
  • To measure how long an event takes, e.g. a race
  • To schedule something to occur at a specific moment

solid

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US / 'sɒlɪd /

UK / ˈsɑlɪd /

A2
  • adjecitve
  • Being able to be trusted; reliable
  • Substance that is hard or of fixed shape
  • Being well made and expected to last long
  • Having no space or emptiness inside
  • Being made entirely of one material or substance
  • noun
  • Something firm or hard; not gas or liquid

through

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US / θru: /

UK / θru /

A2
  • adjecitve
  • having finished using or doing something
  • adverb
  • From the beginning of something until the end
  • preposition
  • Over, in, across an entire thing or place
  • Allowing you to pass between, or to
  • By a particular way or process; by the use of

radially

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US / ˈreɪdiəli /

UK / ˈreɪdiəli /

C1
  • adverb
  • In a radial manner

sound

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US / saʊnd /

UK / saʊnd /

A1
  • adjecitve
  • Sensible, dependable and reliable
  • Unbroken or undisturbed, as of sleep
  • Firm or solid in structure
  • Sane; not mentally ill
  • Clearly reasoned; involving sense, good judgment
  • noun
  • Unique quality that characterizes a style of music
  • Waves traveling in air or water that can be heard
  • verb
  • To seem or appear to be, from what was said
  • To say in a clear deliberate manner
  • To make a noise, e.g. to ring a bell

water

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US / 'wɔ:tə(r) /

UK / ˈwɔtɚ, ˈwɑtɚ /

A1
  • noun
  • Clear liquid that forms the seas, rivers and rain
  • Large area such as an ocean or sea
  • verb
  • (Of the eyes) to produce tears
  • (Mouth) to become wet at the thought of nice food
  • To pour liquids onto a plant to keep it alive

well

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US / wel /

UK / wɛl /

A1
  • adjecitve
  • Being in a fortunate, good condition or state
  • Healthy and in good condition
  • adverb
  • In an acceptable, proper, or successful manner
  • In a complete, total, or full manner
  • A great and considerable degree
  • In a successful way, in a good or satisfactory way
  • exclamation
  • Used to begin or continue a particular statement
  • Used to show you want to start saying something
  • Used to express that you are waiting for a reply
  • You say this to change the topic of a conversation
  • Used to indicate you are making a final remark
  • noun
  • Long deep hole in the ground to get water
  • verb
  • To cause your eyes to fill with tears

amount

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US / ə'maʊnt /

UK / əˈmaʊnt /

A1
  • noun
  • Quantity of something
  • verb
  • To add up to a certain figure

few

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US / fju: /

UK / fju /

A1
  • pronoun
  • Not many, a small number

earth

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US / ɜ:θ /

UK / ɚθ /

A1
  • noun
  • Wire connecting an electrical device to the ground
  • The planet we live on
  • Soil in which we grow plants

perpendicular

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US / ˌpɜ:pənˈdɪkjələ(r) /

UK / ˌpə:pənˈdɪkjəlɚ /

C1
  • adjecitve
  • Being at right angles to a given line or plane

vehicle

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US / ˈvi:əkl /

UK / ˈvi:hɪkl /

A2
  • noun
  • Machine (such as a car) used to carry things
  • Means of expressing, showing, or achieving

line

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US / laɪn /

UK / laɪn /

A1
  • noun
  • Border that divides two places or regions
  • Long crease in the skin, often from age
  • Mark that is long, straight and very thin
  • Row of words, letters or numbers that are written
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  • verb
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just

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US / dʒʌst /

UK / dʒʌst /

A1
  • adjecitve
  • Proper or appropriate; as is deserved
  • Doing or being what is right or fair
  • Legally correct; having enough evidence
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talk

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A1
  • noun
  • Style of speaking
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depend

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US / dɪˈpend /

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B1
  • verb
  • Be controlled or determined by (someone/something)

refraction

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US / rɪ'frækʃn /

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C2
  • noun
  • Light changing direction through glass or water

light

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A1
  • adjecitve
  • Being bright making it easy to see; not dark
  • Being pale and lacking darkness of color
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  • noun
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molecule

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US / ˈmɒlɪkju:l /

UK / ˈmɑlɪˌkjul /

B2
  • noun
  • Two or more atoms chemically combined

occur

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US / əˈkɜ:(r) /

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A2
  • verb
  • To come to pass or to happen

those

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A1
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pack

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  • noun
  • Bag carried on the back of donkey, etc.
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  • Lacking activity, busyness or excitement
  • (Clock) showing time earlier than the actual time
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outward

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B1
  • adjecitve
  • Going away from a place that will be returned to
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visualize

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not

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maybe

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our

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study

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would

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  • other
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angle

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now

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A1
  • adverb
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structure

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A2
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can

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A1
  • noun
  • A metal container for storing food
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want

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weight

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video

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generally

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  • adverb
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  • conjunction
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  • Subtitles section
  • I want to do a quick primer on refraction.
  • And our focus here is going to be on seismic waves.
  • But the principles, how things refract when they go from a fast to a slow medium or slow to a fast medium, it's actually the same as you would see when you're studying light waves or actually any type of wave.
  • So let's think about it a little bit.
  • So let's say I have a slow medium right over here.
  • And let's say I have a fast medium right over here.
  • And let's say, just so that we can travel through both solid and liquid, let's think about maybe P waves.
  • And a slow medium could be maybe some type of liquid.
  • And our fast medium could be some type of solid.
  • So let me draw the boundary right over here.
  • And let's say, so if I have something that comes out P wave, let's say it's going through the water and it's going right perpendicular to the boundary, it will then just continue to travel in the faster medium in the same direction.
  • If it's going right, if it goes right at the boundary, it'll just travel faster in the faster medium.
  • And that's because that faster medium is going to be more dense.
  • And the molecules are going to bump into each other faster.
  • In the same amount of time, more molecules, kind of the chain reaction, is going to be able to travel further because they're more closely packed and they rebound faster than it would in the slow medium.
  • So that's obviously no refraction is going on.
  • It has not been deflected.
  • And just as a bit of a reminder, in general, refraction is when a wave gets deflected.
  • Reflection is when it bounces back.
  • Refraction is when it gets deflected a little bit.
  • Let me just make that clear.
  • So if I have some type of boundary here and I have a wave that bounces off, that's reflection.
  • But if the wave goes through the boundary and just gets bent a little bit, its direction changes, that is refraction.
  • That's what we're talking about.
  • So clearly, so far, this P wave has not been refracted.
  • But if this P wave comes in at an angle, so let's make this P wave come in at an angle, what's going to happen is, and the way you should think about it, it's the easiest way to think about which direction will be refracted,
  • Or at least the way I think about it, is literally I imagine some type of vehicle with wheels on it.
  • So this is the top view of my vehicle.
  • So if I have some type of vehicle, and the wheels will be able to move slowly in this medium.
  • You can kind of view it as kind of on mud so it doesn't get good traction.
  • And then the fast medium, maybe it's a road so it gets good traction and it can move faster.
  • So what's going to happen when the vehicle gets to the boundary?
  • Well, this bottom right wheel is going to go on the fast medium before any of the other wheels do.
  • So it's going to get the traction first.
  • These wheels on the left side of the vehicle, these wheels right here, these are still going to be stuck in the mud.
  • So what's going to happen is, this wheel right over here is moving faster.
  • So it's essentially going to be able to turn the vehicle.
  • These guys are still stuck in the mud.
  • And so you fast forward a little bit.
  • The direction of the vehicle will change.
  • And so the vehicle will now move in a direction something like this.
  • The same thing would happen in a wave.
  • If the P wave is approaching the boundary like this, and something analogous to this is happening at the molecular level.
  • You can kind of view it as even billiard balls, and maybe they're kind of hitting each other.
  • Well, I won't go into that, because that can kind of get a little confusing depending on the different cases and the different boundaries.
  • But this is the easiest way to think about in which direction it'll refract.
  • And hopefully it makes a little bit of intuitive sense.
  • And so when you go from a slow to a fast medium, our P wave, its angle would accentuate in that direction.
  • If you went from the fast medium to the slow medium, once again, you can just go through the same thought experiment.
  • So let's say you have our wave coming in like that.
  • Draw the car.
  • Visualize the car here.
  • Visualize the car right here.
  • And you'd say, well, look, this tire is going to get stuck in the mud, because it was on the road.
  • So now this top tire right over here is getting stuck in the mud first, so it's going to be moving slower.
  • So these tires are going to be able to move faster, so the vehicle is going to turn.
  • So you'll be refracted in a direction like that when you're going from the fast to the slow medium.
  • So that's just a primer on refraction generally.
  • Now let's think about what would happen when sound waves are traveling through the Earth.
  • And this will help inform us of essentially how do we figure out what the actual structure of the Earth is.
  • So if the Earth was just made up of some uniform material, and you had an earthquake right here on Earth, maybe a little bit below the surface.
  • So it's happening in the crust, but a little bit below the surface of the Earth.
  • If Earth was of uniform density, if it was all the same material, how would those, let's just think about the P waves, because P waves can travel in anything.
  • Let's think about how those P waves would travel.
  • Well, they would just go in straight lines.
  • There's nothing that would refract the P waves.
  • It would just go in straight lines, radially outward, from where the earthquake occurred.
  • Now, at a first approximation, we know that as we go deeper and deeper into Earth, there's more and more rock above that.
  • The weight of that rock is kind of compressing the rock below it.
  • So you get higher and higher pressures, and higher and higher densities.
  • So this is a uniform Earth.
  • This is a uniform.
  • But let's imagine an Earth that's made up of uniform material, that's all solid, a completely solid Earth, but one where the density is constantly increasing as you go down.
  • So let's just think about it in, before we go into the continuous case, because we're talking about the density as you go deeper, it's just getting continuously more dense.
  • Let's think about the discrete case, where we have the least dense layer.
  • So let me draw it right over here.
  • So let's say this is the surface of the Earth, and this is least dense.
  • Then let's say you have another layer over here that is more dense.
  • So this is more dense.
  • Let's say you have another layer that's even more dense.
  • So you have another layer over here that's even more dense.
  • And then let's do one more layer.
  • Let's do this layer here.
  • This is the densest layer.
  • So in general, your P wave, your seismic wave, is going to travel faster and denser material.
  • So it's going to travel the fastest here, then here, then here.
  • It's going to travel the slowest in this least dense material.
  • So if you're coming in at an angle, let's think about what's going to happen.
  • So let's say you have your P wave coming in at an angle like this.
  • So it's going straight through the least dense material.
  • Let me do a slightly shallower angle.
  • So let's say it's like that.
  • What's going to happen when it goes into the more dense material?
  • So once again, let's imagine our little car.
  • So this tire is going to be able to go faster before the tires on the other side.
  • So the car is going to be deflected to the left, to the down left.
  • So now it's going to travel like this.
  • So it's now going to travel something like this.
  • Now what's going to happen at this boundary?
  • Once again, imagine the car.
  • This tire right here is going to be able to travel faster before the other tires, so it'll be deflected even more in that direction.
  • Then we go into the densest material.
  • Once again, the tires on the bottom side, when we look at it this way, are going to be able to move faster before the other tires, so we're going to get deflected even more.
  • So you see as you go from least dense material to more dense material, you're kind of curving outward.
  • So if this was continuous, if you had a continuous structure where as you go down, it just gets more and more dense.
  • As you go, so this is less dense, and then it just continuously gets more dense.
  • So this is the most dense down here.
  • How would the refraction look?
  • Well, then it would just be a continuous curve.
  • It would look like this.
  • Your P wave would constantly be refracted out like that.
  • It would curve outwards.
  • So if Earth, so this was the simplest example, where Earth is uniform.
  • And that's pretty easy to dismiss, that obviously things will get denser because of more pressure down.
  • So let's say we assume another thing.
  • We have a uniform Earth in terms of composition, but let's say it gets denser.
  • So denser at the center.
  • Then how would the P waves travel?
  • Then how would the P waves travel?
  • Or how would any seismic waves travel?
  • Well, then if you have your earthquake right over here, the ones that are going straight down still would go straight down, because we know that we won't get refracted if we're kind of going perpendicular to the change in medium or the change in boundaries.
  • But things that are coming at a slight angle, as they get deeper, they're going to get deflected more and more and more and they're going to be refracted outward, just like we saw in this example here.
  • If they go in this angle, they're going to be refracted outward like that.
  • If they go here, they're going to be refracted outward like that.
  • They're going to be refracted outward like that.
  • If you're here, you're going to be refracted outward like that.
  • If you're here, you're going to be refracted outward like this.
  • Now, what we're going to do in the next few videos is use what we just learned about refraction in the case of seismic waves, and hopefully we learned it in this video, and how it would refract as we're going through ever-increasing denser material.
  • We're going to use that information to essentially try to figure out the composition of the Earth based on what we've actually observed.