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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...

can't have done(不可能做过)是must have done(一定做过)的否定形式. couldn't have done(可能没做过)是may have done(有可能做过)的否定形式. 一般认为can't have done有80%以上的把握.而couldn't have done则委婉的多,只有50%左右的把握. ...

“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....

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...

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

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。

could have done 本来能做成的(却没做成) 双语例句: 1.But we could have done it all so much better. 但是,我们本可以把这一切做得更好。 2.If you do a good job, you may tell yourself that it wasn’t good enough or thatanyone could...

mustn't have done: 虽然是推测,但跟事实是一样的,即“一定没有做完某事,以至于对现在还有影响”; He mustn't have done this project. 他必定没有完成这项工程。 但是一般不这样用,而是通常用于反义疑问句,如: He must have done this pro...

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

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