情态动词.docx

1、情态动词English Grammar 情态动词 情态动词 (Model Verbs) 又称为情态助动词 (Model Auxil-iaries)。英语中助动词主要有两类：一是基本助动词，如have, do, be；二是情态助动词，如may, must, need等。情态动词与其他动词连用表示说话人的语气。情态动词可表达建议、要求、可能和意愿等。情态动词没有人称和数的变化。在大学英语四、六级考试中，情态动词部分重点测试以下内容： （1）情态动词+行为动词完成式 （2）情态动词+行为动词进行式 （3）情态动词+行为动词完成进行式 （4）某些情态动词的特殊用法 一、情态动词+行为动词完成式 情态动

2、词+行为动词完成式即“情态动词+ have + v-ed分词”，表示对过去行为或动作进行推测、评论或判断。 1. must have v-ed must have v-ed 表示推测过去某事“一定”发生了。其否定形式为：cant / couldnt have v-ed, 表示过去不可能发生某事。例如： 1）Since the ditch is full of water, it must have rained last night. 2）You couldnt have met my grandmother. She died before you were born. 2. could h

3、ave v-ed could have v-ed 表示推测过去某动作“很可能”发生了。例如： 1）“The dictionary has disappeared. Who could have taken it?” 2）“Tom could have taken it. He was alone yesterday.” 3.may / might have v-ed may / might have v-ed 表示推测过去某事“也许”发生了.may 比 might 表示的可能性在说话人看来稍大些。例如： I cant find my keys. I may / might have left

4、them at the school yesterday. 4. ought to / should have v-ed 和 ought not to / shouldnt have v-ed ought to / should have v-ed 和 ought not to / shouldnt have v-ed 用于对已发生的情况表示“责备”、“不满”，分别表示“本应该”和“本不应该”。例如： 1）With all the work finished, I should have gone to the party last night. 2）You ought not to make

5、 fun of him. He is not the one you laugh at but learn from. 5. neednt have v-ed neednt have v-ed 表示过去做了某事，但没有做的必要， 意为“本没必要”。例如： You neednt have waken me up; I dont have to go to work today. 注：表示推测过去某动作发生的可能性时，就表示的可能性程度而言，must最大，could其次，may更次之，might最小。例如： “I wonder how Tom knew about your past.” “He

6、must / could / may / might have heard of it from Mary.” 二、情态动词+行为动词进行式 情态动词+行为动词进行式（即情态动词+ be + v-ing形式），表示推测或评论某动作现在是否正在进行。例如： 1）He must be playing basketball in the room. 2）She may be staying at home. 三、情态动词+行为动词完成进行式 情态动词+行为动词完成进行式（即情态动词+ have been + v-ing 形式），表示推测或评论过去某动作是否正在进行或一直在进行。例如： 1）They

7、should have been meeting to discuss the problem. 2）He may / might have been buying stamps in the post office when you saw him. 四、某些情态动词的特殊用法 1. need 考试中主要测试 need 作情态动词与作实义动词的区别，对此，可参见表1.need 作情态动词时，后面跟不带to 的动词不定式，即 “need to”。通常用在疑问句和否定句中，表示询问是否有“必要”，其否定形式为neednt，表示“不必”；疑问形式为 Need do? 极少用于肯定句。例如： 1）I

8、 dont think we need turn the light on at that time. 2）Need you ride a bike to school? 情态动词need与实义动词need 在时态、肯定、否定结构上的对比见表1。 2. dare 考试中主要测试dare作情态动词和作实义动词的区别。 情态动词dare 与实义动词dare 在时态、肯定、否定、疑问结构上的对比见表2。 3. can 和 may 考试中主要测试can，may或could，might表示可能性的区别及对may构成的疑问句的回答。 时态 情态动词need 实义动词 need 现 You need (no

9、t) do You (dont) need to do 在 时 He need (not) do He needs (doesnt need) to do 过 You needed (didnt need) to do 去 时 He needed (didnt need) to do 将 You need (not) do You will (not) need to do 来 时 He need (not) do He will (not) need to do 句型 时态 动词 情态动词dare 实义动词 dare 肯定句 现在时 dare to 少用 dare/dares to do 过

10、去时 dare to 少用 dared to do 否定句 现在时 darent/dare not do do/does not dare (to) do 过去时 dared not do did not dare (to) do 疑问句 现在时 Dare he do? Do you/Does he dear (to) do? 过去时 Dared he do? Did he dare (to) do （1）can, could, may, might都可以表示可能性.can, could表示潜在的可能性或理论上或逻辑判断上存在的可能性；而may, might则表示事实上的可能性。此外，can还

11、具有“有能力”的意思，而may与might则不具此意。例如： 1）According to the weather forecast, it may rain tomorrow. 2) Any man with a little sense can see that he is wrong. （2）May I / we ？这一类疑问句的肯定回答为Yes, please.或Certainly；否定回答为Please dont.或No, you mustnt. 例如： “May we leave now?” “No, you mustnt. You havent finished your hom

12、e work yet.” 4. can 和 be able to can 与 be able to 都可以表示能力，但两者在用法上有点差异：can (could)表示主观能力，不表示意愿，它的将来时用will be able to; be able to表示主观意愿，强调要克服困难去做某事。例如： 1）My grandma is over seventy, but she can still read without glasses. 2）He is able to give up his bad habits. 5. must 和 have to must 和 have to 都可以表示“必

13、须”，但有几点区别： （1）must 强调“内在的职责”、“义务”，而have to 强调“外界压力”、“不得已而为之”。 （2）have to可用于多种时态，而must一般用于现在时，其过去时与将来时分别由had to与shall / will have to代替。 （3）在回答must引起的问题时，如果是否定的答复，不能用mustnt，而要用neednt或dont have to，因为mustnt是“一定不要”、“一定不能”的意思。例如： 1）You must come to the classroom before eight. 2）It is raining hard outside,

14、 but I have to leave now. 3）“Must we do it now?” “No, you neednt.” 6. used to +v, be used to +v-ing和be used to +v （1）used to +v意为“过去常常”，“过去一直”；be used to +v-ing / n（名词）意为“习惯于”；be used to +v意为“被用来（做某事）”。 （2）used to只表示过去，而be used to +v-ing / n可表示现在、过去或将来。例如： 1）He used to smoke. Now he doesnt. 2）Hes qu

15、ite used to hard work / working hard. 3）The knife is used to cut bread. 7用作情态动词的其他短语 would rather, would sooner, would (just) as soon, had rather, had better, had sooner, can not but, may (just) as well等可用作情态动词。例如： 1）The soldier would sooner die than surrender. 2）The brave soldier would as soon die

16、as yield to such an enemy. 3）Id rather walk than take a bus. 4）If you dont like to swim, you may just as well stay at home. 注：这些短语后一般直接跟动词原形.would (had) rather, would (had) sooner, would (just) as soon后可跟that 引导的从句，that 常省去，从句要用虚拟语气。对现在和将来的假设用过去时，对过去的假设用过去完成时。例如： 1）I would rather you came on Sunday.

17、 2）I would sooner you hadnt asked me to speak yesterday. 、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cant表示不能。在过去时中用could和couldnt。例如:1.-Wheres Mr Lee? I have something unusual to tell him.-You_find him. He_Japan. (2003黑龙江)A. may not; has gone to B. may not; has been toC. cant; has gone to D. c

18、ant; has been to2.-Finish drawing a horse in ten minutes. OK?-Sorry. It_in such a short time. (2003山东威海)A. may do B. cant be doneC. must do D. neednt be done3. I have my own room in my house, so I_do what I want in it. (2002江西)A. must B. have to C. need to D. can4._you mend my car? I_not start it. (

19、2002常德市)A. Would; would B. Must; must C. Can; can D. May; may5._she ride when she was three years old?( 2002长沙市)A. Can B. Could C. Need D. May6. The boy_answer this kind of hard questions one year ago.(2002四川省) A. can B. may C. couldAnswers: 1. C 2. B 3. D 4. C 5. B 6. Cb.考查can表示推测的用法。在这一用法中,can意为可能

20、,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 much taller. (2003河北)A. mustnt B. may not C. cant D. neednt8. -Listen! Someone is singing in the next room. Who_it be? Is it Wei Fang?-No. It_be her. She is at school now. (2002重庆市)A. will; may not B. must; m

21、ustnt C. may; cant D. may; wont9. -Is Mr Hu in the reading room?-No, he_be there. He has gone to Tianjin. (2002新疆)A. mustnt B. neednt C. wont D. cant10. Class 3 won the football match! _it be true?(2002广东)A. May B. Must C. Will D. CanAnswers: 7. C 8. C 9. D 10. Dc.考查can / could表示请求许可的用法?在这一用法中,can和c

22、ould都表示现在,用could比用can语气更加委婉客气,常用Could I / 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_. (2003武汉)A. could B. can C. will D. might12._you pass me a pen? Id like to write down the telephone number. (2002北京市海淀区)A. Need B. CouldC. Must D. ShouldAnswers: 11.

23、 B 12. B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mustnt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 oclock. (2003安徽)A. can B. may C. must D. need14.-SARS is such a terrible disease.-Yes, it is. We_be more careful. (2003浙江嘉兴)A. can B. may C. mus

24、t D. need15. To make our city more beautiful, rubbish_into the river. (2003重庆)A. neednt be thrownB. mustnt be thrownC. cant throwD. may not throw16. These books_out of the reading room. You have to read them here.(2003辽宁)A. cant take B. must be takenC. can take D. mustnt be taken17. Cars, buses and

25、bikes_stop when traffic lights change to red. (2002上海市)A. can B. may C. must D. needAnswers: 13. C 14. C 15. B 16. D 17. C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 cant. I_take care of my little sister at home because my m

26、other is ill. (2003南京)A. can B. mayC. would D. have toAnswer: 18. D回答must开头的一般疑问句,如果是否定的回答,要用neednt或dont have to,表示不必,没有必要的意思,不用mustnt,因为mustnt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 oclock?-No, you_. (2003四川)A. neednt B. mustnt C. have to20. -_I come back before five oclock?-N

27、o, you_. But you_be back later than seven oclock.(2002烟台市)A. Need; must; mustntB. May; mustnt; cantC. Can; cant; cantD. Must; neednt; cant21. -Must I clean the room right now?-No, you_. You_clean it after lunch. (2002徐州市)A. neednt; canB. neednt; mayC. mustnt; canD. mustnt; mayAnswers: 19. A 20. D 21

28、. Bb.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cant,表示不可能。例如:22. Susans parents have bought a large house with a swimming pool. It _be very expensive. (2003上海)A. must B. can C. mustnt D. cant23. This book_Lucys. Look! Her name is on the book cover. (2002河南)A. must be B. may beC. cant b

29、e D. mustnt beAnswers: 22. A 23. A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 cant.或No, you mustnt.,不用No, you may not.?例如:25. -_I have your name, please?-Yes, Michael. M-I-C-H-A-E-L. (2002北京市东城区)A. Must B. Will C. May D. Need26. -May I go to the cinema, dad?-No, you_. You must finish your homework first. (2002浙江金华市)A. mustnt B. wontC. dont D. neednt27. -May I smoke here?-_, you_. It can be dangerous. (2002滨州市)A. Yes; can B.