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就是can't have seen 我觉得它的结构应该跟couldn't have seen 一样,而只是时态不一样而已

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就是can't have seen 我觉得它的结构应该跟couldn't have seen 一样,而只是时态不一样而已,你认为囊 还有和couldn't see的区别,
就是can't have seen 我觉得它的结构应该跟couldn't have seen 一样,而只是时态不一样而已
一、虽然 could 是can 的过去形式,但是也可以表示现在,取代 can,只不过是在可能性上比 can 略差一些.
二、can't have seen 和 couldn't have seen 在一定得条件下可以互相替换,都是表示说话者当前对过去情况的否定推测.而 can't see 则是说话者对眼下情况的否定推测推测.
三、在表示逻辑判断时,常用下列三种猜测形式:
1.对现在的或然猜测:may + 动词原形
2.对过去的必然性的肯定猜测:nust have + 过去分词
3.对过去的必然性的否定猜测:can't have + 过去分词
如下题就是对过去的必然性的否定猜测:
You can't have seen Kate at the meeting last week; she has been on holiday in London for a month.
其中的判别标志就是句子中有 last week.