情態(tài)動詞must__can__could__may__might表推測的用法

1、情態(tài)動詞must, can, could, may, might表推測的用法：情態(tài)動詞中的must, can, could, may, might都表推測。其中must的可能性最大，can / could次之，may / might最小。具體用法如下：1.must的用法（1）表示推測“可能性”時，意思是“一定、準(zhǔn)是”，語氣較肯定，較有把握。He must be American. = It is certain that he is American. 他準(zhǔn)是個美國人。（2）must表推測只能用于肯定句。如果要表示“一定不、肯定不”的意思時，應(yīng)用cant,如詢問某種可能時，應(yīng)用can。He m

2、ust know my address. 他肯定知道我的地址。（一定） He cant know my address. 他肯定不知道我的地址。（一定不）Can he know my address? 他知道我的地址嗎？（詢問可能性）（3）must表示推測時，可以推測現(xiàn)在/正在發(fā)生的動作/過去發(fā)生的動作。He must have a car now. （現(xiàn)在）他一定有輛小汽車。He must be doing his exercises in the classroom.（正在進(jìn)行）他一定在教室里做練習(xí)。He must have finished the work.（過去發(fā)生）他一定已完成了工

3、作。注：must表示推測時很少用于將來的情況。一般不用He must come tomorrow.可用Its certain / Im sure that he will come tomorrow.（4）在反意疑問句中，當(dāng)附屬部分含有表示推測意義的must時，疑問部分的助動詞應(yīng)與must后面的動詞在非推測情況下的用法保持一致。 He must be a worker, isnt he? （現(xiàn)在）他準(zhǔn)時個工人，是嗎？It must have rained last night, didnt it? （過去）昨晚一定下雨了，是不是？You must have learned English fo

4、r many years, havent you? （完成時）你一定學(xué)了好多年英語，是嗎？2.can / could的用法（1）can表示推測“可能性”時，往往用于否定句或疑問句。Cant“一定不”，語氣很肯定。can在疑問句中意思是“會、可能”。He cant be at home. = It is impossible that he is at home. 他一定不在家。（2）can /cant后可接進(jìn)行時/完成時，表示對現(xiàn)在發(fā)生的動作或過去發(fā)生的動作進(jìn)行推測。They cant be reading in the library. 他們一定不在圖書館讀書。He cant have go

5、ne to Shanghai for I saw him a minute ago. 他不可能去了上海，我剛才還看見他。Its so late. Where can she have gone? 天晚了，她可能去哪兒了呢？（3）在反意疑問句中，當(dāng)陳述部分含有表示推測意義的cant時，疑問部分的助動詞應(yīng)與cant后面的動詞在非推測情況下的用法保持一致.He cant be a teacher, is he? 他不是教師，是嗎？She cant have finished her homework, has she? 她一定沒有完成家庭作業(yè)，是不是？（4）could可用于表示某事有可能發(fā)生或可能是

6、事實(shí)。Dont eat it. It could be poisonous. 不要吃它，可能有毒。The plane could be delayed by fog. 飛機(jī)可能會因?yàn)殪F晚點(diǎn)。 （5）could還可以用于表示客氣、委婉、禮貌的請求語氣。Excuse me, could you tell me the way to the bus station?Could you help me?（6）couldnt表示否定推測，表示某事不可能真實(shí)，或由于特定事實(shí)或環(huán)境某事肯定不會發(fā)生。It couldnt possibly be poison. 這不可能是毒藥。注：有時與形容詞的比較級連用強(qiáng)調(diào)

7、某人或某物不可能再更多地具有某種屬性。You couldnt be more wrong. 你真是大錯特錯。I couldnt be happier. 我簡直是幸福極了。3. may和might的用法（1）may, might表示推測“可能性”時，意思是“可能”、“也許”，語氣沒有 must肯定。He may / might be American. = It is possible that he is American.他可能是個美國人。注：might不表示過去時態(tài)，只是語氣上比may更委婉，表示的可能性更小。（2）may, might表推測時，可以用于否定句，意思是“可能不、也許不”，但

8、不用于疑問句。He may / might not be at home. 他也許不在家。（3）may, might可以推測現(xiàn)在正在發(fā)生的動作或過去發(fā)生的動作。He may / might be sleeping now. （現(xiàn)在）他可能正在睡覺。The boy may / might not be watching TV at home. （現(xiàn)在）這個男孩可能沒在家看電視These students may / might have seen the film before.（過去）這些學(xué)生以前可能看過這部電影。（4）may, might還可以推測將來的情況。I think we shoul

9、d take raincoat with us, it may rain. 我想我們應(yīng)該帶上雨衣，可能要下雨了。She might not come this afternoon. 她今天下午可能不來了。Exercises: Complete the sentences using“must”or“cant”.1. I have tried to call him at the office, but there is no reply. He be at home.2. They have bought a new car. They have a lot of money.3. She i

10、s carrying a Japanese newspaper. She be Chinese.4. He goes abroad a lot, He have an important job.5. She is a professor at the university. She be very clever.6. She is acting in a Shakespeare play tomorrow. She be an actress.一.Choose the best answers to complete the following sentences:1. I thought

11、you like something to read. So I have brought you some books.A. ought B. might C. could D. must2. That man must be Sarahs husband.-No, he be her husband. She is still single.A. cant B. mustnt C. may not D. ought to3. Peter come with us tonight, but he isnt very sure.A. must B. may C. can D. will4. W

12、hat it be?-It be a mail box, for it is moving. It be a car.A. can; cant; must B. can; can; mustC. can; mustnt; must D. must; mustnt; can5. Look, someone is coming. Guess .-Jack. Hes always on time.A. who can it be B. who he mayC. who he can be D. who it can be6. I saw Mary in the library yesterday.-

13、You her. She is still abroad.A. mustnt see B. cant have seen C. mustnt have seen D. couldnt see7. David, you play with the valuable bottle, you break it.A. wont; cant B. mustnt; mayC. shouldnt; must D. cant; shouldnt8. Susan refuses to marry Jack now. She her mind.A. must change B. should have chang

14、edC. must have changed D. would have changed9. Sue come together with us tonight, but she isnt very sure yet.A. must B. may C. need D. will10. Aunt Margaret the rain, otherwise she would have arrived here by now.A. must have missed B. should have missedC. had missed D. might miss二.Fill in the blanks

15、 using must / can / could / may / might and their negative forms.1.Could I borrow your dictionary?-Yes, of course you .2. She doesnt answer the bell. She be asleep.3. The ground is wet. It have rained last night.4. He is writing with a pencil. He have lost his pen.5. A computer think for itself, it be told what to do.6. There is much gas here, you smoke here.7. Was he present at the meeting?-He not have attended it, for he was busy repairing his car all the time.8. Look! An old man