情态动词完成时的推测

must have done 对过去的非常肯定的 推测 （语气最强）
1) They must have gone there last night, didn't they? 对已发生的过去情况的推测，若陈述 句谓语部分有“must have done”， 而且有表示过去的时间状语, 问句部 分用didn't；
have received -- ____Mr King _____________the Can letter? 金先生已经收到那封信了吗？ --No, he can __________________it. ’t have received 不，他不可能收到。
may/might have done 用于肯定句 某事有可能发生过 和否定句 (表示对过去的不太肯定的推测， (may的语气 语气比must have done 弱)
比might稍强)
---Where did Adam get that new football? He hasn’t got any money. ---It ____ a present. After all, it was his birthday last week. A. might have been B. might be
wishes it had
(not) happened.
needn ’t have done
indicating that it
is not necessary for sb. to do sth, though he / she did it.
You needn’t have watered the plant. It rained last night.
is possible that
something
happened or was
They might have mistaken you.
true (used only in
positive/ negative
sentences)
should/ shouldn ’t have done
You should indicating that have done something did your not / did happen, homework but the speaker first.
They must have been to the World Expo last week, _____ ____? didn’t they
疑问句 can done can ’thave have done 对过去的否定推测 对过去的疑问推测 和 否定句
--Where is John? Can he have gone to the playground? --No, he can’t have gone to the playground It is raining.
Why is the road It must have rained so wet? last night.
A: Where are the girls? Can they have gone home? B: No, they can’t have gone home. It’s so early.
这个房间昨天肯定被清扫了。 The room _____ ______ must _____ have _____ been cleaned yesterday.
他一定已经背了5000单词了。
He ____ must ____ have _____ learnt 5,000 words.
You must have seen the film “Journey haven’t you to the West” , _______ ____?
He ______out because the light was on.
A. may not have gone
B. may have not gone
C. may not go
D. must not have gone
needn’t have done 本没有必要做某事 （但此事已做）
We ___________________the needn’t have watered plant because it rained last night. (本无必要)
答案为 D。虚拟语气用法。句意：--我明天要告诉她我的新工作的情 况。 ---你本应该上周告诉她。
4. — Tom graduated from college at a very young age. — Oh, he ____ have been a very smart boy then. （04 全国IV） A. could B. should C. might D. must 答案为 D。表推测的用法。句意：—— 汤姆很年轻的时候就大学毕业了。—— 哦，他肯定是一个很聪明的男孩儿。
Finding the rule
Modal verbs Explanations + have done must have Believing what done happened in the past is the case (used only in positive sentences) Example sentences It must have rained last night.
--Look, the lights are off in their room. --Where have they gone? --They might have gone to the cinema.
A: Here is a doll for your daughter. B: Thank you so much. It’s beautiful. But you needn’t have bought it. She has so many at home.
2. I have lost one of my gloves. I _____
it somewhere. （05 北京春季）
A. must drop
B. must have dropped C. must be dropping D. must have been dropped
3. Mr. White ___ at 8:30 for the meeting, but he didn't show up. （04 广西） A. should have arrived B. should arrive C. should have had arrived D. should be arriving 4. He paid for a seat, when he ___ have entered free. （05 山东卷） A. could B. would C. must D. need
off the alarm clock and gone back to sleep again. （2000 北京春季） A. might B. should C. can D. will 答案为 A。表推测的用法。句意：对 不起, 我迟到了。我(当时)兴许是关 了闹钟又回去睡觉了。might 相当于 may, 但语气更加不肯定。
答案为 B。虚拟语气用法。句意：我 （那时）真地很担心你。你本不应该 不留个话就离开家。
3. — I’ll tell Mary about her new job tomorrow. — You__ her last week. （04 福建） A. ought to tell C. must tell B. would have told D. should have told
2)They must have arrived by now, haven’t they? 对已发生的过去情况的推测，若陈述 句谓语部分有“must have done”， 若没有表示过去的时间状语，问句部 分用haven’t 或hasn’t .
3) He must have been to the Great Wall, hasn't he? 对已发生的过去情况的推测，若陈述 句谓语部分有“must have done”， 若没有表示过去的时间状语，问句部 分用haven’t 或hasn’t .
练习 1. — The woman biologist stayed in Africa studying wild animals for 13 yearபைடு நூலகம் before she returned. — Oh, dear! She ___ a lot of difficulties! (05 江苏卷) A. may go through B. might go through C. ought to have gone through D. must have gone through
--Where is John? Can he have gone to the playground? --No, he can’t have gone to the playground. It is raining.
may/ might have done
Suggesting that it
can/ could have done
indicating that something was a possibility in the past , though it did not actually happen (negative or interrogative sentences)
shouldn’t have done 本不该做某事 （但此事已做）
表示责备
should have done 本应该做某事 （但此事未做）
表示责备
He should have repaired the bike yesterday.
Oh, I'm not feeling well in the stomach. I shouldn’t have eaten so much fried chicken just now.
你本应该先完成你的作业。 You _____ ____ _______ should have finishedyour homework first.
你本不应该跟我撒谎。
You ________ ____ ____to shouldn’ t have lied me.
高考例析
1. Sorry I’m late. I _____ have turned
2. I was really anxious about you. You____ home without a word. (01 全国) A. mustn't leave B. shouldn't have left C. couldn't have left D. needn't leave
5. He _____ have completed his work; otherwise, he wouldn't be enjoying himself by the seaside. (05 北京卷) A. should B. must C. wouldn't D. can't
答案为 B。用法同4题。句意：他 肯定做完了工作，不然他就不会 在海边痛快地玩儿了。
6. — Do you know where David is? I couldn’t find him anywhere. — Well. He ____ have gone far— his coat’s still here. （05湖北卷） A．shouldn't B．mustn't C．can't D．wouldn't 答案为 C。表推测的用法。句意：—你 知道大卫在哪儿吗？我哪儿也找不到 他。—瞧，他不可能走远—他的上衣还 在这儿呢。can't 相当与 couldn't，但 后者语气更加委婉。