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CAn hAvE DonE和CoulD hAvE DonE有无区别?CAn't h...

情态动词 + have done 动词 + 动词完成式即“情态动词 + have + done”,表示对过去行为或动作进行推测、评论或判断。这个结构是近几年高考情态动词的重点和难点。 一、在虚拟语气中的用法 1. should have done 表示“过去本应该做某事却未做。”其...

“would+have+done”虚拟语气,表示对过去事情的假设,意思是“本来会做”。 1. I would have told you all about the boy's story, but you didn't ask me. 我本来会告诉你这个小男孩的故事,但是你没有问我。 2. Without your help, I wouldn't ha...

“can't+have+done”表示对过去事情的否定推测,译成“不可能做过某事”。 Mr. Smith can't have gone to Beijing, for I saw him in the library justnow. 史密斯先生不可能去北京了,我刚才还在图书馆见过他。 Mary can't have stolen your money....

could have done 表示本能做而实际未做,是虚拟语气。 can have done 和could have done 还能表示对过去的推测,常用于否定句和问句中。

第一could语气较为委婉

因为是已经过去了的事情,所以用could,而非can;因为是完成了的事情,是完成时,所以要用have。简单地说因为是上个星期,而且是事情已完成,用过去完成时! 另一种解释:这是without引导的隐蔽形虚拟语气,和过去事实相反的,用could+现在完成时。

cPursue your object, be it what it will, steadily and indefatigably.,

我的理解 could have done:猜测而已,心里没底 would have done:认为问题不大,也是猜测,但较为乐观

would/could /should/needn't+have done 表示本来……实际却没有 本来想要/能够/应该/不必做某事 而实际上却相反 must/may/might/can't+have done表示对过去发生的情况进行推测 过去一定是/可能是/也许是/一定不是 should to do/ shouldn't to do...

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 thro...

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