I' m afraid I must be off now . It' s time I ________ to work .

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A．go 　　B．should go

He ________ go today than tomorrow.

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A．would rather　　　　B．prefer to

There is a rocket motor ________ the direction of the satellite can be changed.

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A．by which　　　　B．by it

There are many research stations on the earth ________ outer space is studied.

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A．in which　　　　B．on them

She spent the afternoon ________ the window and the floors.

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A．to wash　　　　B．washing

After reviewing the new words, he ________ the text.

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A．went on to explain　　　　B．went on explaining

Would you please tell me when the meeting__________?

［　　］

_________ the youngsters are fond of R&B.

［　　］

Shirley ____ a book about China last year, but I don't know whether she has finished it.

[　　]

He is very nervous. I noticed his hand ____.

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