can't have been,must have been 结构里是不是不要把have been当现在完成时看,就把它

来源：学生作业帮编辑：作业帮分类：英语作业时间：2024/11/06 08:43:58

can't have been,must have been 结构里是不是不要把have been当现在完成时看,就把它当成一个结构来使用?

have用于“情态动词＋have＋过去分词”的结构,有
推测、假设之意.
1.must＋have＋过去分词,表示对过去时间发生的动作或存在的情况的推测,一般用于肯定句.
Her father thought that she must have met a fairy.
You must have left your bag in the theatre.
2.can(could)＋have＋过去分词,表示对过去发生事情的“不肯定”,常用于否定句和疑问句.
He can't have been to your home,he doesn't know youraddress.
3.should＋have＋过去分词,表示“某事本该早做而实际未做”,用于肯定句.
You should have been here five minutes ago.

can't have been,must have been 结构里是不是不要把have been当现在完成时看,就把它 must have been和can't have been和现在完成时有没有联系啊 can't have been和must have been 关于现在完成时have been 现在完成时的have been be,must be,can't have been,must have been吗 They can't have been doing thier homework.have been 是现在完成时,但 He can't have been ill是现在完成时? 关于must have been MUST have been done must have been 用must have been/done或can*t have been/done 改写句子