The moon has been visited by ________ already.

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I ________ English for 4 years.

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Our rooms must ________ clean and tidy.

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It ________ every day so far this week.

[　　]

The scientists use satellites for ________?

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After that, he lived ________ 5 years.

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Spring comes. It is the best time for ________ trees.

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________ years ago, coal came from trees and other plants that grew on earth.

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________you ________ finish your work tomorrow?

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A．Will, can

B．Will, be able to

C．Can, be able to

D．Can, will

[　　]

A．shall we　　　　　B．don't we

C．will we　　　　 　D．won't we