1. may (might)＋have＋过去分词都可以表示对过去情况的一种推测，但是，might＋have＋过去分词的推测可能性更小一点：对过去的推测则用“may＋have＋p.p.”(主要用于肯定或否定句)：
Human error may have been a contributing factor.
人为的失误可能是一个起作用的因素。
A bolt may have fallen off the plane's forward door.
飞机前舱门的一个门闩可能脱落了。
We apologize for the delay and regret any inconvenience it may have caused.
我们对此次延误以及因此有可能造成的所有不便表示道歉。
You may have misheard her ─ I'm sure she didn't mean that.
你可能听错她的话了——我肯定她不是这个意思。
They may have weaponized quantities of anthrax.
他们可能已将大量炭疽制成了武器。
He may have missed his train.
他可能没赶上火车。
He may have put pressure on her to agree.
他可能向她施加了压力，迫使她同意。
He may have been to some of those places
那些地方他也许去过一些。
I may have made a mistake in that regard.
我在那一点上可能已经犯了一个错误。
She may not have the money to maintain or restore her property.
她可能没有足够的钱来维护或修葺她的房产。
I may not have mentioned it to her.
我可能没跟她提过这件事。
The pupil's answers may not have been reflective of what the class as a whole had understood.
这个学生的回答也许并不能代表该班级整体的理解。
It tears me apart to think I might have hurt her feelings.
一想到我可能伤害了她的感情，我就感到痛心。
I ventured to suggest that she might have made a mistake.
我小心地提醒说她可能出了差错。
The pills might have helped him, if only he'd taken them regularly.
他当时要是按时服药，也许可以对他有帮助的。
She might have been killed if the neighbours hadn't intervened.
要不是邻居介入，她可能会没命了。
Perhaps your force of argument might have made some difference.
或许是你的雄辩使情况发生了变化。
But for you, they might have given us the slip.
要不是你，我们可能已经被他们甩掉了。
The bill might have gone through if the economy was growing.
要是当时经济在增长的话，该法案或许也就获得通过了。
I might have been disposed to like him in other circumstances.
若是处于另一番情形的话，我可能会倾心于他。
Things might have been different if I'd talked a bit more.
如果当时我再多说一点的话，结果或许会不一样。
He might have let something slip in a moment of weakness.
他可能一时大意说漏了嘴。
She thought the shooting might have been an accident.
她想这次枪击可能是一次意外。
It sounds as if they might have made a dreadful mistake.
听起来他们似乎犯下了一个可怕的错误。
I thought you might have invited her over.
我以为你可能已经邀请她过来了。
Someone might have guessed our secret and passed it on.
有人或许已经猜到了我们的秘密并且将其散布开了。
This is something which you might have forgotten.
这事儿你可能已经忘记了。
The letter might not have been meant for me at all.
这封信也许根本就不是写给我的。
The equipment needed to clean up the spill might not have arrived yet.
清理漏油所需要的设备可能还没有送到。
I didn't give my name because if I did I thought you might not have come.
我没有留下我的名字，因为如果我这么做的话，我想你可能就不会来了。
2. might have done 还可以表示责备：含有本来应该怎么可是没有做
You might have told me that before!
你之前应该告诉我那件事情！
You might have phoned to let us know where you were. 你应该打个电话让我们知道你在哪。
The report might have been better written.
这份报告本来可以写得更好。
You are late again. You might have come earlier.
你又迟到了。你本来应该早一点到的。
He might have had the decency to apologize.
他其实应该道个歉的。
3.might have done还表示报怨或不满：表示对所谈论的情况不满或有抱怨，主要用于guess, know, suspect等动词。如：
I might have guessed he’d fail to read the instructions. 我早就知道他不会看说明书的。
I might have known you would take that attitude. 我就知道你会是那样的态度。
4. 对现在或将来的推测用“may＋动词原形”; 对过去的推测则用“may＋have＋p.p.”(主要用于肯定或否定句)：
It may rain tomorrow. 明天可能下雨。
He may be a good father but he's a terrible husband.
他或许是一位好父亲，但却是个很糟糕的丈夫。
He may have said so. 他也许这样说过。
They may not have known it before. 他们以前可能不知道此事。
5. 若是推测正在进行的动作也可用may＋be＋doing：
He may be waiting for us. 他也许在等我们。
I may be stating the obvious but without more money the project cannot survive.
我这话可能多余，但是不投入更多资金，项目就难以为继。
表示推测的may一般都可以用might代之。以上各例中表推测的may均可换为might，只是语气不那么肯定。但是以下两种情况通常要用might，而不用may：
(1) 表示说话者对没有做某事进行责备：
You might have helped her. 你本来可以帮她的!
(2) 用于疑问句：
Might this be true? 这可能是真的吗?
Might he have been waiting long? 他可能已等了很久吗?