情态动词记忆口诀:情态动词两要点;动词原形跟后面,说话语气较委婉,can表"能力"may"许可",must"责任"或"义务",否定回答"needn't"换;should"应该",would"愿",have to "被迫"表客观.注释:对must构成的一般疑问句作否定回答只能用needn't.情态动词有can (could), may (might), must, have to, shall (should, will (would), dare (dared), need (needed), ought to等。
情态动词无人称和数的变化；不能单独使用，必须与其后的动词原形构成谓语一、can, could1) 表示能力（体力、知识、技能）。
Can you lift this heavy box?（体力）Mary can speak three languages.（知识）Can you skate?（技能）此时可用be able to代替。
Can只有一般现在时和一般过去式；而be able to则有更多的时态。
I’ll not be able to come t his afternoon.当表示“经过努力才得以做成功某事”时应用be able to，不能用Can。
如：He was able to go to the party yesterday evening in spite of the heavy rain.2) 表示请求和允许。
-----Can I go now?----- Yes, you can. / No, you can’t.此时可与may互换。
在疑问句中还可用could, might代替，不是过去式，只是语气更委婉，不能用于肯定句和答语中。
---- Could I come to see you tomorrow?---- Yes, you can. ( No, I’m afraid not. )3) 表示客观可能性（客观原因形成的能力）。
They’ve changed the timetable, so we can go by bus instead.This hall can hold 500 people at least.4) 表示推测（惊讶、怀疑、不相信的态度），用于疑问句、否定句和感叹句中。
Can this be true?This can’t be done by him.How can this be true?二、may, might1) 表示请求和允许。
might比may语气更委婉，而不是过去式。
否定回答时可用can’t或mustn’t，表示“不可以，禁止”。
----Might/ May I smoke in this room?---- No, you mustn’t.---- May/Might I take this book out of the room?---- Yes, you can. (No, you can’t / mustn’t. )用May I...？征徇对方许可时比较正式和客气，而用Can I...？在口语中更常见。
2）用于祈使句，表示祝愿。
May you succeed!3) 表示推测、可能性（不用于疑问句）。
might不是过去式，它所表示的可能性比may小。
1．He may /might be very busy now.2．Your mother may /might not know the truth.三、must, have to1) 表示必须、必要。
You must come here on time.在回答引出的问句时，如果是否定的，不能用mustn’t（禁止，不准），而用needn’t, don’t have to（不必）.---- Must we hand in our exercise books today?---- Yes, you must.---- No, you don’t have to / you needn’t.2) must是说话人的主观看法，而have to则强调客观需要。
Must只有一般现在时，have to 有更多的时态形式。
1．His play isn’t interesting, I really must go now.2．I had to work when I was your age.3) 表示推测、可能性（只用于肯定的陈述句）1．You’re Tom’s good friend, so you must know what he likes best.2．Your mother must be waiting for you now.3. The road is wet. It must have rained last night. 马路湿了，昨晚一定下雨了。
（must加完成式，说明对过去事物的推测，表示“一定”或“准是”的意思。
）四、needneed 作情态动词用时, 常用于疑问句、否定句。
在肯定句中一般用must, have to, ought to, should代替。
1．You needn’t come so early.2. ---- Need I finish the work today?---- Yes, you must. / No, you needn’t.3) need作实义动词用时，有人称、时态和数的变化。
1.The house needs to be painted.2. The house needs painting.3. He needs to finish his homework today.五、shall1) shall 用于第一人称，征求对方的意见。
What shall we do this evening?2) shall 用于第二、三人称，表示说话人给对方的命令、警告、允诺或威胁。
1. You shall fail if you don’t work hard.(警告)2. He shall have the book when I finish it.(允诺)3. He shall be punished.(威胁)六、will, would1) 表示请求、建议等，would更委婉。
Will / Would you pass me the ball, please?2) 表示意志、愿望和决心。
1. I will never do that again.2. They asked him if he would go abroad.3) would表示过去反复发生的动作或某种倾向。
would表示过去习惯时比used to正式，且没有“现已无此习惯”的含义。
1. During the vacation, he would visit me every other day.2. The wound would not heal.4) 表示估计和猜想。
It would be about ten o’clock when she left home.七、should, ought to1) should, ought to表示“应该”，ought to表示义务或责任，比should语气重。
1. I should help her because she is in trouble.2. You ought to take care of the baby.2) 表示劝告、建议和命令。
should, ought to可通用，但在疑问句中常用should。
1. You should / ought to go to class right away.2. Should I open the window?3) 表示推测should , ought to (客观推测), must(主观推测)。
1.He must be home by now. (断定他已到家)2.He ought to/should be home by now.(不太肯定)3. This is where the oil must be.(直爽)4. This is where the oil ought to/should be.(含蓄)总结一、猜测: must, may, might, can, couldmust只能用于肯定句,非常肯定的猜测may只能用于肯定句,表示可能的猜测can只能用于否定/疑问句,过去时用couldshould 表示预测“应当”二、情态动词否定式的常考点有：mustn’t 禁止、严禁、不准needn’t 不必要、没必要(=don’t have to)can’t不可能may not可能不、或许不shouldn’t不应该（=ought not to )三、情态动词+ have done表示对过去发生的事情的推测,批评,反悔等意should have done 本应该做而没做ought to have done 本应该做而没做could have done 本可以做而没做needn’t have done不必做的做了may/ might have done可能做了某事(猜测)must have done一定做了(猜测)can’t have done一定没有做(猜测)练习题1)A computer ___think for itself, it must be told what to do.A. can’tB. couldn’tC. may notD. might not2).The fire spread through the hotel very quickly but everyone ____ get out.A. had toB. wouldC. couldD. was able to3)--Where is my uncle, Mary?--He ___ in the bedroom.A. must have beenB. must beC. may have beenD. should have been4)Peter ___ come with us tonight, but he isn’t very sure yet.A. mustB. mayC. canD. will5) --That must be a mistake.--No, it ___ a mistake.A. must not beB. needn’t beC. can not beD. would not be6) It’s nearly 7 o’clock. Dad ___ come home soon.A. canB. couldC. wouldD. should7)--Are you coming to Jeff’s party?--I’m not sure. I ___ go to the concert tonight.A. mustB. wouldC. shouldD. might8)You ___ return the book now. You can keep it till next week if you like.A. can’tB. mustn’tC. needn’t9)Johnny, you___ play with the knife, you ___ hurt yourself.A. won’t; can’tB. mustn’t; mayC. shouldn’t, mustD. can’t; shouldn’t10).I didn’t hear the phone. I ___ asleep.A. must beB. must have beenC. should beD. should have been11).I didn’t see her in the meeting room this morning. She ___ at the meeting.A. mustn’t have spokenB. shouldn’t have spokenC. needn’t have spokenD. couldn’t have spoken12).I can’t find Mr. Smith anywhere in the office building. Where ___ he have gone?A. mustB. canC. shouldD. need高考考题:1. I thought you _____like something to read, so I have brought you some books.A. mayB. mightC. wouldD. must2. Where is my pen? I ____it.A. might loseB. would have lostC. should have lostD. must have lost3. I didn’t hear the phone. I ___asleep.A. must beB. must have beenC. should beD. should have been4. ---There were already five people in the car, but they managed to take me as well.----It ____a comfortable journeyA. can’t beB. shouldn’t beC. mustn’t have beenD. couldn’t have been5. It’s nearly seven o’clock . Jack ___be here at any moment.A. mustB. needC. shouldD. could6. They will ______ run this machine on their own in three months.A. canB. couldC. mayD. be able to7. That big cinema ______ seat 2,000 people.A. canB. shouldC. ought toD. is able to8. — Could I borrow your dictionary?— Yes, of course you _______.A. mightB. willC. canD. should9. — Might I watch TV after supper?— Yes, you ________.A. mayB. mustC. mightD. can10. --Will you stay for lunch?--Sorry, _____. My brother is coming to see me.A. I mu stn’tB. I can’tC. I needn’tD. I won’t11. --May I pick a flower in the garden?-- ________.A. No, you needn’tB. Not, please.C. No, you mustn’tD. No, you won’t12. Put on more clothes. You ________ be feeling cold with only a shirt on.A. canB. couldC. mustD. would13. "Must I drive to his house and pick up the children?""No, ________ ."A. you shouldn'tB. you might notC. you needn'tD. you mustn't14. We didn't see Tom at the meeting yesterday. He ________it.A. mustn't have attendedB. cannot have attendedC. needn't have attendedD. would have not attended15. We ________ play chess than bridge. Some of us don't know how to play bridge.A. had betterB. would betterC. would ratherD. had rather16. There is someone knocking at the door. ________ it be Tom?A. canB. mustC. shouldD. ought to17. Two years ago, my husband bought me a bicycle. If you live in town, it is often faster than a car and you ________ worry about parking.A. must notB. may notC. should notD. don't have to18.--Is John coming by train?--He should, but he ____ not. He likes driving his car. (2002高考题）A. mustB. canC. needD. may19.It has been announced that candidates(候选人)____ remain in their seats until all the papershave been collected. (2002上海高考题）A. canB.willC. mayD. shall20.--I heard they went skiing in the mountains last winter.--It ____ true because there was little snow there. (2002北京高考题）A. may not beB. won’t beC. couldn’t beD. mustn’t be情态动词强化练习(作业)1.–May I sit beside you, sir?--- No, you ______. My girlfriend is coming soon.A. can’tB. mustn’tC. needn’tD. shouldn’t2.-- _____ I speak to Mary, please?--Sorry, she____ come to the phone because she isn’t in.A. Might; won’tB. Can’t; mustn’tC. May; can’tD. Couldn’t; shouldn’t3. --- I want to know if I _ smoke here.--- No, you____ . Could you see the sign “NO SMOKING” there?A. can; needn’tB. must; can’tC. shall; won’tD. may; mustn’t4. My wife never remembers my telephone number. She always ____ look it up.A. mustB. shouldC. wouldD. has to5. --- ____ you pass me the English magazine, please?--- Sure. Here you are.A. CouldB. NeedC. MustD. Might6. ---Must I go to work with you?--- No, you_____. Linda ______ go with me.A. mustn’t; canB. can’t; has toC. daren’t; shouldD. needn’t; may7. --- __ I tell Mary the test results?--- No, you____. She’s already got the score.A. Will; won’tB. Shall; needn’tC. May; mustn’tD. Can; don’t8. You ____ be careful when crossing here. The traffic lights aren’t w orking.A. mightB. ought toC. couldD. may9. ---Could I borrow your bicycle?--- Yes, of course you_____.A.willB. shouldC. canD. need10. Joan_____ come with us this afternoon, but she isn’t very sure yet.A. canB. mayC. mustD. will11. I _____ ask you the question because I think I _____ be wrong.daren’t; must B. mustn’t; canC. needn’t; mayD. can’t; should12. It’s nearly eight o’clock. Mike _____ be here at any moment.A. needB. has toC. shouldD. can13. The fire spread through the building very quickly but everyone ____ get out.A. had toB. wouldC. couldD. was able to14.---What do you think of this answer?---I don’t think it ____ be right.A.shouldB. mightC. mustD. can15. --- Is John coming by train?--- He should, but he ___. He likes driving his car.A. can’tB. needn’tC. may notD. mustn’t16. He doesn’t have to w ork tomorrow, but you have got to, ____ you?A. don’tB. haven’tC. haven’t gotD. can’t17. You_____ wake me up when I fall asleep, ______ you?A. haven’t better; haveB. would not rather; wouldC. had better not; shouldD. had not better; must18. ---Why! I couldn’t get you on the phone this morning.--- We _____ tennis in the yard when you phone me.A. could be playingB. must be playingC. must have been playingD. should have played19. --- We didn’t see him at the lecture.--- Neither did anybody else. He _____ it.A. may not have attendedB. mustn’t attendC. can’t have attendedD. couldn’t attend20. ---I came here by taxi and the driver charged me 50 yuan.---Really? You _____ have come by bus.A. couldB. mustC. mayD. should21. --- Do you still remember when we went to the Great Wall?--- I can’t remember it well, but _____ it have been sometime last May?A. shouldB. mustC. couldD. would22. ---I wonder why M r Lin didn’t come to work.--- He____ have been ill.A. needn’tB. shouldC. mightD. can23. ---No one passed the mathematics examination today.---I guess we ____ the exercise last night.A. could reviewB. should reviewC. might reviewD. should have reviewed24. She_____ the hospital so soon, for she hasn’t yet recovered.A. wouldn’t have leftB. shouldn’t have leftC. needn’t leaveD. hadn’t left25. Why didn’t you tell me there was no meeting today? I ______ all the way here throug h the heavy snow.A. needn’t have drivenB. can’t have drivenC. must have drivenD. shouldn’t have driven.26. The book is neither yours nor mine. Whose ______ it be?A. mustB. mayC. shouldD. can27. It is surprising that he ____ have been so foolish.A. mustB. couldC. shouldD. can28. It must have rained last night, _____ it?A. mustn’tB. can’tC. hasn’tD. didn’t29.---Will you stay for lunch?--- Sorry, I _____. My brother is coming to see me.A. mustn’tB. can’tC. needn’tD. won’t30. --- Are you coming to Jeff’s party?--- I’m not sure. I ____ go to the concert instead.A. mustB. wouldC. shouldD. might.31. Michael ____ be a po liceman, for he’s much too short.A. needn’tB. can’tC. shouldD. may32. Mr Bush is on time for everything. How ___ it be that he was late for the ceremony?A. canB. shouldC. mayD. must33. –I stayed at a hotel while in New York?-- Oh did you? You ____ with Barbara.A. could have stayedB. could stayC. must have stayedD. would stay34. If I ___go with you, I would feel very glad.can B. could C. should D. may35.There was a lot of fun at yesterday’s party. You___ come, but why didn’t you?A. must haveB. shouldC. need haveD. ought to have36.—When can I come for the photos? I need them tomorrow afternoon.--They ___ be ready by 12:00.A. canB. shouldC. mightD. need37. I didn’t hear the phone. I ____ asleep.A. must beB. must have beenC. should beD. should have been38. I ___ do all the difficult work for you.A. haven’t got toB. not have got toC. have got not toD. have got to not39. Sorry I’m late. I ___ have t urned off the alarm clock and gone back to sleep again.A. mightB. shouldC. canD. will40. If I had time, I ____ go with you.A. canB. willC. mayD. might参考答案练习题1-5 ADBBC 6-10 DDCBB 11-12 DB高考考题1-5 BDBDC 6-10 DACAB 11-15 CCCBA 16-20 ADDDC情态动词强化练习1-5 ACDDA 6-10 DBBCB 11-15 ACDDC 16-20 BCCCD21-25 CCDBA 26-30 DCDBD 31-35 BAABD 36-40 BBAAD。