考试
2020-03-16 06:24:23

9696 In recent years, a number

题目描述

In recent years, a number of communication satellites ______ into orbit about the earth.A.



In recent years, a number of communication satellites ______ into orbit about the earth.

A.have been put

B.has been put

C.are already put

D.have been putting

请帮忙给出正确答案和分析,谢谢!

答案解析

A本题综合考查主谓一致、时态和语态。据题

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