1、情态动词 must, can, could, may, might 表推测的用法 情态动词中的 must, can, could, may, might 都表推测。其中 must 的可能性最大，can / could 次之，may / might 最小。具体用法如下：1.must 的用法（1）表示推测“可能性”时，意思是“一定、准是” ，语气较肯定，较有把握。He must be American. = It is certain that he is American. 他准是个美国人。（2）must 表推测 只能用于肯定句 。如果要表示“一定不、肯定不 ”的意思时，应用 cant,如询问某
2、种可能时，应用 can。He must 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? 他知道我的地址吗？（询问可能性）（3）must 表示推测时，可以推测现在发生的动作，正在发生的动作和过去发生的动作。He must have a car now. （现在）他一定有辆小汽车。He must be doing his exercises in the classroom.（正在进行）他一定在教室里做练习。He must have finished
3、 the work.（过去发生）他一定已完成了工作。注：must 表示推测时很少用于将来的情况。一般不用 He must come tomorrow.可用 Its certain / Im sure that he will come tomorrow.（4）在反意疑问句中，当附属部分含有表示推测意义的 must 时，疑问部分的助动词应与 must 后面的动词在非推测情况下的用法保持一致。 He must be a worker, isnt he? （现在）他准时个工人，是吗？It must have rained last night, didnt it? （过去）昨晚一定下雨了，是不是？Y
4、ou must have learned English for many years, havent you? （完成时）你一定学了好多年英语，是吗？2.can / could 的用法（1）can 表示推测“可能性”时，往往用于否定句或疑问句 。Cant “一定不” ，语气很肯定。can 在疑问句中意思是“会、可能” 。He cant be at home. = It is impossible that he is at home. 他一定不在家。（2）can /cant 后可接进行时 /完成时，表示对现在发生的动作或过去发生的动作进行推测。They cant be reading in
5、the library. 他们一定不在图书馆读书。He cant have gone to Shanghai for I saw him a minute ago. 他不可能去了上海，我刚才还看见他。Its so late. Where can she have gone? 天晚了，她可能去哪儿了呢？（3）在反意疑问句中，当陈述部分含有表示推测意义的 cant 时，疑问部分的助动词应与 cant 后面的动词在非推测情况下的用法保持一致.He cant be a teacher, is he? 他不是教师，是吗？She cant have finished her homework, has s
6、he? 她一定没有完成家庭作业，是不是？（4）could 可用于表示某事有可能发生或可能是事实。Dont eat it. It could be poisonous. 不要吃它，可能有毒。The plane could be delayed by fog. 飞机可能会因为雾晚点。 （5）could 还可以用于表示客气、委婉、礼貌的请求语气。Excuse me, could you tell me the way to the bus station?（6）couldnt 表示否定推测，表示某事不可能真实，或由于特定事实或环境某事肯定不会发生。It couldnt possibly be poi
7、son. 这不可能是毒药。注：有时与形容词的比较级连用强调某人或某物不可能再更多地具有某种属性。You couldnt be more wrong. 你真是大错特错。I couldnt be happier. 我简直是幸福极了。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” ，语气没有 must 肯定。He may / might be American. = It is possible that he is American. 他可能是个美国人。注：might 不表示过去时态，只是语气上比 may 更委婉，表示的可能性更小
8、。（2）may, might 表推测时，可以用于否定句，意思是“可能不、也许不 ”，但不用于疑问句。He may / might not be at home. 他也许不在家。（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. （现在）他可能正在睡觉。The boy may / might not be watching TV at home. （现在）这个男孩可能没在家看电视These students may / might have seen the film before.（过去）这些学生以前可能看过这
9、部电影。（4）may, might 还可以推测将来的情况。I think we should take raincoat with us, it may rain. 我想我们应该带上雨衣，可能要下雨了。She might not come this afternoon. 她今天下午可能不来一、单项选择1 John_ come to see us tonight, but he isnt very sure yet. A. may B. need C. cant D. must 2 John isnt in the classroom. He play soccer on the playgro
10、und with Bob.A. can B. must C. should D. cant3 -Will you go to the cinema with us? -No, I rather read a magazine at home.A. should B. might C. would D. had better4 You_ go and see a doctor at once because you got a fever.A. can B. must C. dare D. would5 -Can you speak Japanese? -No, I_. A. mustnt B.
11、 cant C. neednt D. may not 6 -He_ be in the classroom, I think. -No, he _ be in the classroom. I saw him go home a minute ago. A. can; may not B. must; may not C. may; cant D. may; mustnt 7 -Is Lena swimming in the pool? -No, she swim. She is terrified of water.A. may not B. must not C. cant D. need
12、nt8 He isnt at school. I think he _ be ill.A. can B. shall C. must D. might9 -What do you think “upset” means? - Im not sure. It mean “sad”.A. may B. must C. can D. should 10 The children_ play football on the road. A. cant B. can C. mustnt D. must 二、根据句子意思用 must, might, could 或 cant 填空1. The white
13、ruler belong to Lucy. Hers is red.2. I cant find my keys. They be still at home.3. The exercise book belong to Bob. It has his name on it.4. Jim be at home. He has gone to his hometown.5. This blue shirt belong to Ken. He likes blue best.6. The schoolbag be Pauls. There are a lot of books in it.7. T
14、he volleyball belong to Alice. She plays volleyball every day.8. The classroom is clean. Someone clean it just now.9. Is that Bob there? No, it be him. He has gone to Shanghai with his family10. where is Mr. Lee? The light in his bedroom is still on. He be there.11. I find my pencil case. I think I
15、have lost it.12. The boy is clever. He tell many stories when he was young.13. The man is running fast. He be catching the bus.14. Li Lei has learned English for 15 years. He know the meaning of this sentence.15. What are you going to do this weekend ? Im not sure. I visit my grandparents.16. Who is
16、 that boy in blue?It be Tim. He is always reading English there every morning.It be him. He is talking with Miss Liu in the classroom.17. I thought you _ be hungry, so I have brought you some cakes.18. -Here are some earrings. The owner _ be a boy.-Well, it _ be a boy. The earrings _ be a present fo
17、r his mother.19.-Are you coming to Jeffs party? -Im not sure. I go to the concert instead20. I have tried to call him at the office, but there is no reply. He be at home.三、根据所给汉语提示完成句子。1. 他脸色苍白,准是病了。He looks so pale, he 2. 她戴着钻石项链，一定很有钱。Shes wearing a diamond necklace. She 3. 他现在可能正在打篮球。He basketbal
18、l now. 4. 我确信她不在家。Im sure that she stay at home.5. 他肯定在花园里散步。He in the garden.6. 这本字典肯定是我的，上面有我的名字。The dictionary mine. It has my name on it. 7. 这张 CD 可能是属于 Tony 的，因为他喜欢听流行音乐。The CD belong to Tony because he likes listening to pop music.8. 这个发带不可能是鲍勃的，终究他是个男孩。The hair band be Bobs. After all, he is
19、a boy!9气温可降至60，也就是零下 60。The temperature fall to 60, that is 60 below freezing. 10她可能不知道这件事。11他担心他们可能不同意他的意见。He was afraid 12你辛苦干一整天，一定累了You have worked hard all day. 13. 再等十分钟，我弟弟可能正开车到这里来。Wait another 10 minutes! My brother here now.14.公园里现在肯定有一些老人正在散步。There some old people taking a walk in the park now.15. 别玩小刀，你可能会伤到自己的。Dont play with the knife. You
