情态动词的推测用法.doc

情态动词的推测用法一、 在肯定句中表示较有把握的推测用must， 意为“想必一定……”1) 对目前状态的推测，用must + be + 表语a. --- Where is Mary? ---She must be in the library.b. The story he told us must be true. 2) 对目前动作的推测，用must + 行为动词a. She must know Beijing very well, for she has been there several times.3) 对正在发生事情的推测，用must + be + v-ing a. He must be waiting for us at the school gate.4) 对已经发生或过去发生的事情的推测，用must + have + p.p.a. She must have cried, for her eyes are still red. b. It must have rained last night, for the ground outside is wet.5) 对已经发生并一直在持续的事情的推测，用must + have + been + v-inga. You look tired. You must have been working all day long.二、can (could) 作推测时，用法有如下3种：A) 在否定句中，表示有把握的否定推测，意为“不可能……”1) 对目前状态的否定推测，用can’t + be + 表语 a. Don’t worry. The information can’t be true. 2) 对目前动作的否定推测can’t + 动词a. The boy is honest. He can’t tell lies. 3) 对正在发生事情的否定推测，用can’t + be + v-ing a. They can’t be watching TV, for the electricity has been cut off.4) 对已经发生或过去发生的事情的否定推测，用can’t + have + p.p. a. She can’t have read that book, for she knows nothing about it.b. Jenny can’t have been with him at that time, for I was having dinner with her in my home.c. You can’t have seen him at the party last night. I saw him off at the airport yesterday afternoon.5） 对已经发生并一直在持续的事情的否定推测，用 can’t + have + been + v-inga. They can’t have been practicing. You see, they haven’t made any progress.b. --- John walked straight into a wall.--- He couldn’t have been looking where he was going.B) 在疑问句中，对事情的可能性提出疑问，表示“可能吗？会不会？”1) 表示对现在的推测，用Can / Could + S + v. ?; a. --- Can it be true? --- No, it can’t be true. b. Where can they be now?2) 对过去的推测用Can / Could + S + have + p.p.a. Can he have left yesterday?C) 在肯定句中，表示“有时候可能会”：a. It can be very cold here in winter.b. ---Your daughter is well behaved. ---Yes, but not always. Sometimes she can be very naughty.三、 在肯定句或否定句中，表示对事情把握不大的推测，用may (或 might)。

might 比 may 表示的可能性更小，意为“可能……; 或许……”1) 对目前动作的推测，用may + 行为动词a. He may get here anytime.b. Jack may not know this news.2) 对目前状态的推测，用may + be + 表语a. He may be at home. Let’s go and see. b. The story may not be true. 3) 对正在发生事情的推测，用may + be + v-ing a. They may be watching TV at home now.b. They may not be playing in the garden now.4) 对已经发生或过去发生的事情的推测，用may + have + p.p.a. He may have heard of the news.b. It may (might) have rained during the night. c. She may not have learned English when she was at school.5) 对已经发生并一直在持续的事情的推测，用 may + have + been + v-inga. The boy may have been playing computer games all the morning, for his eyes are red.b. How do they know we went out? They may have been watching us.情态动词做推测用法的练习1 --Look, it _____ be Mr. Wang. –No, it _____ be him. He has gone abroad.a. may, mustn’t b. must, may not c. must, can’t d. can, may not2 --Tom is never late for work. Why is he absent today? --Something ____ to him.a. must happen b. should have happened c. could have happened d. must have happened3 --Do you know where David is? I couldn’t find him anywhere.--Well. He _____ have gone far—his coat’s still here.a. shouldn’t b. mustn’t c. can’t d. wouldn’t4 Aunt Catherine _____ the train, otherwise she would have arrived here by now.a. must have missed b. should miss c. didn’t d. doesn’t5 He must have seen the famous writer last night, _____ he?a. mustn’t b. hasn’t c. didn’t d. doesn’t6 --Mr. Smith must have lost his way, for he hadn’t arrived yet.--No, he _____ have lost his way. He has got a map with him.a. mustn’t b. should c. can’t d. may7 If there is a strike of bus drivers, they _____ walk to school tomorrow.a. must have b. had to c. may have d. may have to8 He _____ have completed his work; otherwise he wouldn’t be enjoying himself by the seaside.a. should b. must c. wouldn’t d. can’t9 Helen _____ go on the trip with us, but she isn’t quite sure yet.a. shall b. must c. may d. can10 Mary _____ be in London because I saw her in town just now.a. mustn’t b. isn’t able to c. may not d. cannot11 --There is no light in the room. --_____he be sleeping?a. Must b. Shall c. Can d. Will12 It ____ he that tells such a lie; it ____ you.a. must not be, must be b. can’t be, must be c. must not be, can be d. can’t be, can be13 All the students in Class 8 passed the physics exam. It _____ have been difficult.a. must b. mustn’t c. shouldn’t d. can’t14 --I can’t get through to my office.--The line is busy. Someone _____ the telephone.a. must use b. must be using c. should use d. can be using15 Lily _____ read the novel, for she knows nothing about it.a. can’t have b. mustn’t c. can’t d. mustn’t have16 --Do you still remember that summer holiday when we went together to the summer pala。