,情态动词 modal verbs,表示能力: can, could, be able to *be able to 能用于各种时态。 can / could 只能表示现在或过去的能力。 *was / were able to : “设法做成某事” 相当于 managed to do sth. succeeded in doing sth.。,一. 表示能力、许可的情态动词的用法。,1. A computer _ think for itself; it must be told what to do. A. cant B. couldnt C. may not D. might not,2. The fire spread through the hotel very quickly but everyone _ get out. A. had to B. would C. could D. was able to,A,D,3. They will _ run this machine on their own in three months. A. can B. could C. may D. be able to,D,二表示许可: may / might, can / could * might, could 比较委婉, 一般多用于疑问句. * can, may 表达的语言比较随便. * 在以could, might 表示征询对方意见 或表示请求时，回答应相应使用can, may.,5. Could I borrow your dictionary? Yes, of course you _. A. might B. will C. can D. should 6. Might I watch TV after supper? Yes, you _. A. may B. must C. might D. can,C,A,三. 表示否定的情态动词的用法:,mustnt 不准, 禁止 neednt 没必要 ( = dont have to ) cant 不能; 不可能 may not 不可以; 可能不 shouldnt 不应该 ( = ought not to ) wont/ wouldnt 不愿意 darent 不敢,四 can/may/must/need 问句的回答方式,疑问句式,肯定句式,否定答式,you may.,mustnt/may not.,you must,neednt/dont have to.,you must.,neednt/dont have to.,情态动词的应答 1. - Shall I tell John about it? - No, you _. Ive told him already. (N 1994) A. neednt B. wouldnt C. mustnt D. shouldnt 2. - Could I call you by the first name? - Yes, you_. (1998上海) A. will B. could C. may D. might,A,C,此句的关键是“Ive told him already”，由此可见，你就不必再对他说了。,在回答 “Could I ”这类婉客气的请求时，只能回答“Yes, you can 或 may”。不能用 could 或 might。,3. - Will you stay for lunch? - Sorry, _. My brother is coming to see me. (N 1999) A. I mustnt B. I cant C. I neednt D. I wont 4. - Write to me when you get home. - _. (2001北京春季) A. I must B. I should C. I will D. I can,B,C,此句的关键是 “My brother is coming to see me.” 所以我不能在这儿吃饭。,在回答对方的请求或命令时，应该用 “Yes, I will.”而不能使用 would 或 should。,5. You _ return the book now. You can keep it till next week if you like. A. cant B. mustnt C. neednt D. may not 6. Johnny, you _ play with the knife, you _ hurt yourself. A. wont ; cant B. mustnt ; may C. shouldnt ; must D. cant ; shouldnt,C,B,7. -Will you stay for lunch? -Sorry, _. My brother is coming to see me. A. I mustnt B. I cant C. I neednt D. I wont 8. -May I pick a flower in the garden? - _. A. No, you neednt B. Not, please. C. No, you mustnt D. No, you wont,B,C,五 表示推测情态动词的重要用法.,肯定的推测 可能的推测 否定的推测 疑问的推测,ust/should,对将来 对现在 对过去,情态动词,may, might,cant, couldnt,can, could,+ V. + V. + have done 常见must be + be doing,+ V. + V. + have done + be doing 可以用not表示“可能不”,+V. + V. + have done + be doing,+ V. + V. + have done + be doing,1. The ground is rather wet, so it _ have rained last night, didnt it? 2. Tom _ have gone to Shanghai, but Im still not sure about it. 3. The ground is very dry, so it _ have rained last night. 4. Someone must have broken into our bedroom. Who _ have done it? 5. I really regretted wasting the hours when I _ have studied hard, but it was too late.,must,may,cant,could,should,6.Your home is not far from your school, so you _ have left in such a hurry then. 7. I _ have come to help you with your English, but I was too busy at that time.,8. -I paid a visit to New York last month and we stayed at a nice hotel. -Oh,you _have stayed with Barbara.She is always willing to do you a favour.,could,neednt,would rather,六 情态动词+完成式： 1. must have done 2. may/might have done 3. cant/ couldnt have done 4. should /ought to have done 5. shoulnt/oughtnt to have done 6. could have done 7. neednt have done 8. would rather have done,1. You must be Mr Smith-I was told to expect you here. 2. He must have known what we wanted. 3. We may have read the same report. 4. He cant have slept through all that noise. 5. Theres someone outside-who can it be? 6. What can they be doing? 7. These pills might help to cure your disease. 8. You could be right, I suppose.,1. I dont know where she is, she _ be in Wuhan. 2. At this moment, our teacher _ our exam papers. 这时，我们老师想必在批改试卷。 3. The road is wet. It _ last night. (rain) 4. Your mother _ for you. 你妈妈一定一直在找你。,may,must be marking,must have rained,must have been looking,5. Philip _ seriously in the car accident. 菲利普可能在车祸中受了重伤. 6. -Linda has gone to work, but her bicycle is still here. -She _ (go) by bus. 7. Mike _ his car, for he came to work by bus this morning. 迈克一定还没有找回他的车，因为早上他是坐 公共汽车来上班的。,may have been hurt,may have gone,cant have found,七 shall,1.He shall be punished if he disobeys. 2.If you work well, you shall have higher wages. 3.According to the law, half