1，情态动词表推测
must表示推测时，可以推测现在/正在发生的动作/mouchu过去发生的动作。
He must have a car now. 自费留学（现在）他一定有辆小汽车。
He must be doing his exercis in the classroom.（正在进行）他一定在教室里做练习。
He must have finished the work.（过去发生）他一定已完成了工作。
2，can’t/couldn’t+ have done，表示对过去发生的动作进行推测。
He can't have gone to Shanghai for I saw him a minute ago. 我怎么了英语
他不可能去了上海，我刚才还看见他。
3， may和might的用法
（1） may, might表示推测“可能性”时，意思是“可能”、“也许”（3）may, might可以推测现在正在发生的动作或过去发生的动作。
He may / might be sleeping now.
The boy may / might not be watching TV at home.
华尔街官网这个男孩可能没在家看电视
The students may / might have en the film before.
（过去）这些学生以前可能看过这部电影。
He may / might be American. = It is possible that he is American.
他可能是个美国人。
例题
1–That man must be Sarah’s husband.
herschel--No, he_____ be her husband. She is still single.
roger什么意思A. can't B. mustn't C. may not D. ought to
2 Peter _____come with us tonight, but he isn't very sure.
mokoA. must B. may C. can D. will
3–I saw Mary in the library yesterday.
--You_____ her. She is still abroad.
A. mustn't e B. can't have en C. mustn't have en D. couldn't e
lucky boys
2，情态动词表虚拟
should have done过去本来应该（而实际上并没有…)
should not have done 过去本不应该做…而实际上却已经…”
如：1、We should have studied last night, but we went to the concert instead . 我们昨晚本应学习的，但我们却去看音乐会了。（实际上没有学习）
could have done它表示“过去本来能够…” 实际上没能做…。
could not have done它表示“过去本来不能够…” 实际上却做成了…。
如1、I could have run 100 meters in 12 conds.
我本来能用12秒钟完100米的.（实际上没能）
2aroud、If you had finished the task in time，you could have been promoted.
如果你当时能如期完成那任务的话，你可能已提升了（实际上没有被提升）
would have done 用在虚拟语气中,表示与过去事实相反之假设的结果，常与if 引导的条件句连用。
（1）I would have helped you if I had known of your difficulties . 要是我当时知道你们的窘境，我就会帮助你了（而实际上没有帮助你）
(2) If it hadn't rained yesterday, we would have gone out for a walk .假如昨天没下雨，我们就去散步了。（实际上没有去）
might have done过去本来可以（而实际上并没有…)
might not have done 过去本不可以做…而实际上却已经…”
I might have pasd the exam, but I failed.
1.Mr White ____ at 8:30 for the meeting, but he didn't turn up.
A. should have arrived B. should arrive
C. should have had arrived D. should be arriving
pupil怎么读2. If he had been here yesterday, he ______ this pop star.
A. would meet B. would have met
C. met D. must have met
