________ the students in our class is 50 and ________ them study hard.

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A．The number of; the number of

B．A number of; the number of

C．The number of; a number of

D．A number of; a number of

Some languages, ________ Russian and German, are not easy to learn.

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Don't keep your mouth ________ if you want to improve your ________ English.

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On my way ________, I met an old school friend of mine.

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When my hand touched the letter in my pocket, I realized that I had forgotten ________ it.

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After living in Paris for fifty years he returned to the small town ________ he grew up as a child.

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I hadn't meant ________ you. Instead, what I said really meant ________ you to be good.

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There were twelve ________ in the party.

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We drove all the ________ to Boston and was just in time for the concert.

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If you go on doing that kind of thing, you'll ________ prision.

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