hdpe七孔梅花管:四选一选择题

来源:百度文库 编辑:高考问答 时间:2024/05/14 04:34:56
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Something ______ to save the forests on the mountains.
A. has done B. did C. has been done D. have been done

C 主语是动作的被执行者,所以用被动,根据语意判断用现在完成时

C现在完成时