could have done "本来可以……"(表示过去没有实现的可能)。 might have done "本来可能……;本来应该或可以做某事"(实际没有发生;含有轻微的责备语气。 should/ought to have done "本来该做某事"(而实际未做) should not/ought not to have done "本来不该做"(实际...
A. not to do B. not to be done C. not to have done D. not having done 3、I' m sorry I couldn't get in touch with him before he left, I ___ him earlier. A. had a telephone B. have phoned C. should have phoned D. should be phoned 4、He...
1)can could 表示能力;可能(过去时用could), 只用于现在式和过去式(could)。be able to可以用于各种时态。They will be able to tell you the news soon.他很快就能告诉你消息了。 2)只用be able to a. 位于助动词后。 b. 情态动词后。 c. 表示过去某时刻动作时。
could have done sth.( could have done sth.)。(情态助动词could与完成时形式的动词不定式have done sth.连用)表示过去可能会发生但实际上没有发生的事情: You could have got a job last year. 你本来去年就可能会找到工作的。(实际上没有找到)
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