Question

The country has already sent up three unmanned spacecraft, the most recent __________ at the end of last March.

A. has been launched     B. having been launched

C. being launched   D. to be launched

Answer 1

C。

解析:

由于动作于去年的三月底就已经发生，所以不能选表示未来动作的不定式，即不能选D; 又由于句子用了具体的过去时间状语(at the end of last March)，故不能选完成式，即不能选A和B。