情态动词一.情态动词的定义：情态动词表示说话人对某一动作或状态的态度。

二.情态动词的特点： 1.有一定词义； 2.不受主语人称和数的变化影响；3.与主要动词的原形（或称不带to的不定式）一起构成谓语（除ought to，have to作固定词组看待）。

三.情态动词的基本用法一、考查can的用法a.考查can表示能力的用法。

在这一用法中,can表示能力,意思是"能,会",其否定式can't表示"不能"。

在过去时中用could 和couldn't。

例如:1.-Where's Mr Lee? I have something unusual to tell him.-You________find him. He________Japan.A. may not; has gone toB. may not; has been toC. can't; has gone toD. can't; has been to2.-Finish drawing a horse in ten minutes. OK?-Sorry. It________in such a short time.A. may doB. can't be doneC. must doD. needn't be done3. I have my own room in my house, so I________do what I want in it.A. mustB. have toC. need toD. can4.________you mend my car? I______not start it.A. Would; wouldB. Must; mustC. Can; canD. May; may5.________she ride when she was three years old?A. CanB. CouldC. NeedD. May6. The boy________answer this kind of hard questions one year ago.A. canB. mayC. could注意：can 和be able to1.情态动词can只有两种时态形式，现在式can和过去式could，而be able to有多种时态形式。

Mary can play the piano. She has been able to play it since she was 5.玛丽会弹钢琴。

她五岁起就会弹了。

2.用在过去时中，could经常表示能够做某事，事实上不一定去做，而was∕were ableto则表示“过去做成了某事”。

在否定句中两者可通用。

He couldm across the English Channel. But he didn't feel like it that day.他能游过英吉利海峡，但那天他不想游。

Yesterday I was able to get home before the heavy rain昨天我在下大雨前赶到了家里。

b.考查can表示推测的用法。

在这一用法中,can意为"可能",表示客观可能性,常常用于疑问句和否定句中。

例如:7. Who is the man over there? Is it Mr Li? -No, it________be him. Mr Li is muchtaller.A. mustn'tB. may notC. can't D . needn't8. -Listen! Someone is singing in the next room. Who________it be? Is it Wei Fang?-No. It________be her. She is at school now.A. will; may notB. must; mustn'tC. may; can'tD. may; won't9. -Is Mr Hu in the reading room? -No, he________be there. He has gone toTianjin.A. mustn'tB. needn'tC. won'tD. can't10. Class 3 won the football match! ________it be true?A. MayB. MustC. WillD. Canc.考查can / could表示请求许可的用法?在这一用法中,can和could都表示现在,用could比用can语气更加委婉客气,常用CouldI / you...?句式,表示"我/你能……吗?"若表示同意要用can,不用could?例如:11.-Could I look at your pictures? -Yes, of course you________.A. couldB. canC. willD. might12.________you pass me a pen? I'd like to write down the telephone number.A. NeedB. CouldC. MustD. Should二、考查must的用法a.考查must表示义务的用法。

在这一用法中,must意为"必须","应该",表示必须要做的事,其否定式mustn't表示禁止,即不许对方做某事?例如:13.-May I go to the cinema, Mum? -Certainly. But you________be back by 11 o'clock.A. canB. mayC. mustD. need14.-SARS is such a terrible disease. -Yes, it is. We________be more careful.A. canB. mayC. mustD. need15. To make our city more beautiful, rubbish________into the river.A. needn't be thrownB. mustn't be thrownC. can't throwD. may not throw16. These books________out of the reading room. You have to read them here.A. can't takeB. must be takenC. can takeD. mustn't be taken17. Cars, buses and bikes________stop when traffic lights change to red.A. canB. mayC. mustD. need要注意must和have to的用法区别?must表示说话人的主观看法,而have to表示客观的需要,意思是"不得不"?例如:18. -Can you go swimming with us this afternoon?-Sorry, I can't. I________take care of my little sister at home because my mother is ill.A. canB. mayC. wouldD. have to句式变化区别：回答must开头的一般疑问句,如果是否定的回答,要用needn't或don't have to,表示"不必","没有必要"的意思,不用mustn't,因为mustn't表示禁止或不许,意思是"一定不要"的意思。

例如:19. -Must I finish the work before five o'clock? -No, you________.A. needn'tB. mustn'tC. have to20. -________I come back before five o'clock?-No, you________. But you________be back later than seven o'clock.A. Need; must; mustn'tB. May; mustn't; can'tC. Can; can't; can'tD. Must; needn't; can't21. -Must I clean the room right now?-No, you________. You________clean it after lunch.A. needn't; canB. needn't; mayC. mustn't; canD. mustn't; mayb.考查must表示推测的用法。

在这一用法中,must意为"一定","肯定",表示可能性很大,通常用于肯定句,在否定句中要用can't,表示"不可能"。

例如:22. Susan's parents have bought a large house with a swimming pool. It ____be very expensive.A. mustB. canC. mustn'tD. can't23. This book________Lucy's. Look! Her name is on the book cover.A. must beB. may beC. can't beD. mustn't be三、考查may的用法a.考查may表示请求许可的用法在这一用法中,may表示许可或征询对方许可,表示"可以"的意思,常常与第一人称I连用,构成May I...?句式,表示"我可以……吗?"肯定回答用Yes, you may.; Yes, please.等;否定回答用No, you can't.或No, you mustn't.,不用No, you may not.?例如:25. -________I have your name, please? -Yes, Michael. M-I-C-H-A-E-L.A. MustB. WillC. MayD. Need26. -May I go to the cinema, dad? -No, you________. You must finish your homework first. A. mustn't B. won't C. don't D. needn't27. -May I smoke here? -________, you________. It can be dangerous.A. Yes; canB. No; can'tC. Yes; mayD. No, needn'tAnswers: 25. C 26. A 27. B②测试may表示可能性的用法。