Ice and snow ________ houses in the North Pole.

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The plan sounds ________.

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--________ we play football here?

--No, you mustn't.

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When he ________ the classroom, we were talking about the film.

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The more he read, the more questions he thought ________.

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We should keep our earth ________.

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The meat is ________ expensive and eating ________ is bad for our health.

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What he is in charge of ________ the reading contest.

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________ we've finished the job, let's have a rest.

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It's ________ useful bird and it is ________ unusual bird, too.

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