题目内容
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
B
考查独立主格结构。根据the end of last March可知动作已经发生,故用现在分词的完成时,因句中的逗号,后用独立主格结构。
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