1、情态动词＋动词的完成式couldhavedone表惋惜could have done 表示过去能够做而实际未做。意为“本来能够做到,而实际没做”，有惋惜、遗憾之意。或用来提出婉转的批评。could have done 表示过去能够做而实际未做时，仅用于肯定句。有惋惜、遗憾之意，或表委婉批评。In those circumstances we could havedone better.在那样的情况下，我们本来可以做得更好。（但实际没有做得更好）You could have done better, but you didn’t try
2、your best.你本可以做得更好，但是你没有尽力而为。我们本可以完成任务，但是一直下着雨。We could have finished the task, but it was always raining.你本可以把它全部给我的。You could have given it all to me.你本可以更加整齐一点儿。You could have been a little bit tidier.couldhavedone表推测过去She could have gone off with some friends.她可能和几个朋
3、友出去了。This glass is cracked. Someone could have dropped it.这个玻璃杯破了。可能是谁把它掉在地上了。钱不见了！会是谁拿走的呢？可能是汤姆拿走的；昨天只有他一个人在这儿。The money has disappeared! Who could have taken it?Tom could have taken it; he was here alone yesterday.Can...havedone?表怀疑“Can…have done”意为“难道真的做了吗”，表示不相信。Can
4、they have left so soon?难道他们这么快就走了?Can he have done such a foolish thing? (= Is it possible …?)他会做这样的傻事吗？她可能丢失了那笔钱吗？Can she have lost the money? (=I doubt whether…)他会丢下工作不干了？Could he have left the work unfinished?can‘thavedone表不可能“can’t have done”表否定推断，推测肯定没做。The measurem
5、ent couldn’t have been wrong.测量不可能出错了。He can’t have been to that town他根本不可能去过那座城市。他不可能把它带回家了He can't have taken it home.“can’t have done”表“不可能”“mightn’t have done”表“可能不”。mightn‘thavedone表可能不“mightn’t have done”表“可能不”。They mightn’t have regarded me as their friend.他们可能没有把
6、我当作朋友看待。我爸爸可能没有受到责备。My father mightn’t have been to blame.双亲大人可能对这次的怀孕还没有做好准备。The parents mightn’t have been ready for this pregnancy.mayhavedone推测过去“may(might)+动词的完成式”表示“对过去发生的行为的推测”。may have done 表推测时，隐含“不确定”。might have done 表推测时，隐含的“不确定性”比“may have done”更深。他可能还没有完成那项工
7、作。He may not have finished the work.他们事先可能不知道这事儿。They may not have known it beforehand.你可能在报上已经看过这个消息了。You might have read about it in the papers.wouldhavedone"would＋动词的完成式"表示对过去的某种情况进行猜测，或本来要做某事却因某种原因未做成，通常用来说明某一情况，但不像用should或ought to那样含有责备之意。I guess the poet would have
8、 been about twenty when she wrote her first poem.我猜这位诗人写第一首诗歌的时候，大概20岁左右。Another worker wouldn't have a
