可用mustn't have done表示对过去的推测吗?若可以,那这个结构与can't have done有区别吗?可以的话,请提供相应的信息来源.本人不甚感激~
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可用mustn't have done表示对过去的推测吗?若可以,那这个结构与can't have done有区别吗?可以的话,请提供相应的信息来源.本人不甚感激~
可用mustn't have done表示对过去的推测吗?若可以,那这个结构与can't have done有区别吗?
可以的话,请提供相应的信息来源.本人不甚感激~
可用mustn't have done表示对过去的推测吗?若可以,那这个结构与can't have done有区别吗?可以的话,请提供相应的信息来源.本人不甚感激~
首先have done表示已经做过,这点就不用谈了.
can't have done 表示以前不可能做某事.
例句
---Where____Margaret have put the empty bottles?
---She________them away.They must be somewhere.
A.can;can't have thrown
B.must;must have thrown.
C.must;needn't
D.can;must throw
答案为A.第一个句子是一个疑问句而且表示可能性的推测,所以只能用情态动词can或could,第二句的答语表示对过去的推测,所以用can't have done.
请看常见的“情态动词 + have + 过去分词”的用法:
一、“must + have + 过去分词”表示对过去发生的事情或状态进行推测,语气比较坚定,通常只用于肯定句.如:
It must have rained last night,for the ground is wet.
You must have been mad to speak to the servant.
二、“can / could + have + 过去分词”表示对过去某种情况的怀疑或不确定.can和could一般用于否定句和疑问句,could的语气较can弱.如:
I didn't see her at the meeting this morning; she can't / couldn't have spoken at the meeting.
He can't have finished the work so soon.
不可以用mustn't have done表示对过去情况的否定推测,只能用can't have done
肯定则可以用must have done