In recent years, a number of communication satellites ______ into orbit about th

游客2025-03-21 43

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

选项 A、have been put
B、has been put
C、are already put
D、have been putting

答案 A

解析本题综合考查主谓一致、时态和语态。据题意，近几年来，许多通讯卫星已经被发射到环绕地球的轨道。由于用了时间状语In recent years，所以时态应为现在完成时；anumber of意思是"许多"，谓语要用复数。

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