Text books ________ to come out in time.

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Text books ________ to come out in time.

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At the entrance all passengers _____ to show their tickets.

A. required       B. are required       C. require        D. are requiring

从所给的四个选项中选择最佳答案

Text books ______ to come in time．　　　

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A．require　　　B．required　　　C．are required　　　D．are requiring