问题描述:
The experiment _____ last week.
A.ought to be done B.ought to do C.ought to have been done D.ought to have done
为什么?我选A不对吗?为什么用现代完成时?过去时不行吗?既然是应该过去做为什么不用过去完成时?
A.ought to be done B.ought to do C.ought to have been done D.ought to have done
为什么?我选A不对吗?为什么用现代完成时?过去时不行吗?既然是应该过去做为什么不用过去完成时?
问题解答:
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