Englishfor English speakers
exchange
Verb
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Two people exchange two things when each person gives a thing to the other person. They can exchange two things, or they can exchange a thing for money.
The children can exchange toys so that each child has a new toy to play with.
exchange
Noun
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An exchange is the act of exchanging.
I did well in that exchange. Now I have three good new books, and I only paid a little money.
rate
Noun
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Speed. A rate is how fast something happens. Something can go at a fast rate or a slow rate.
The rate of water pouring out of the lake into the river is enough to make the lake empty in a year if it doesn't rain.
Her heart rate is 70 beats every minute.
If we keep writing pages at this rate we might have 2000 Simple English Wiktionary words by August 4.
rate
Verb
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Someone rates something when they decide how much its value is (how much it's worth).
I rate this book at six out of ten: it was not the best book.
index
Noun
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An index is an alphabetical (A to Z) list, usually at the back of a book, where you can find the pages in a book that talk about particular things or words.
Look in the index to see where they talk about Chomsky.
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An index shows the level of prices, wages, etc. so you can compare them with those of an earlier date.
On Wall Street, the Dow Jones index closed 10 points up at 2,731.23.
index
Verb
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If you index something, you make an index (guide) for it.
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If you index something to a certain price level, you make it go up or down with that level.