情态动词专题讲解1.docx

1、情态动词专题讲解1情态动词专题讲解一情态动词(Model Verbs)的语法特征情态动词主要有can, may, must, could, might, shall , should, will, would, ought to, need, dare等。1） 情态动词不能表示正在发生或已经发生的事情，只表示期待或估计某事的发生。2） 情态动词 除ought 和have 外，后面只能接不带to 的不定式,即动词原形。3） 情态动词没有人称，数的变化，即情态动词第三人称单数不加-s。4） 情态动词没有非谓语形式，即没有不定式，分词等形式。二. 情态动词的基本用法1) can、could和be a

2、ble to can和be able to都表示能力(Ability)，意思上没多大区别。但can只有现在和过去时，而be able to则有更多的形式。但当成功地完成某一具体动作时，通常不用could而用was/were able to来表示。这时was/were able to表示经过一番努力，终于能够完成某事, 在许多情况下又可以交替使用。如： Can you use chopsticks?I cant do it now, but I can do it later.Is there anything I can do for you. The wounded man still wa

3、s able to get to the village and was saved in the end.As I have got enough money, I can / am able to help her.can和couldcan和could都可以表示能力、技能、许可、建议或请求和可能性。但比较委婉客气地提出问题或陈述看法，一般用could，回答时则用can。但在肯定句中， could 所表示的“能力”仅是泛指过去的一般能力。如：Could you help me carry the bag?She could play the piano when she was only s

4、ix.Can I help you?在疑问句表示“可能”， 须用can 而不用may。如：Where can he be? He may be in the office.Can they have missed the bus? Yes, they may have.2) must 和 have to must 和 have to 都可以表示“必须”，但有几点区别： 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”。 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

5、代替。 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。如： You must come to the classroom before eight. It is raining hard outside, but I have to leave now. “Must we do it now?” “No, you neednt.” 3） shallshall作为情态动词用于第二、三人称，表示说话人的意愿，有“命令”、“警告、威胁、强制”和“允许”等意思。如： We shall

6、do as our teacher says. You shall have the book as soon as I finish it.在疑问句中，shall用于征求对方的意见或请求指示，常用于第一、第三人称。如： Where shall he wait for us? / Shall we go out for a walk? 4) need的用法 need既可用作情态动词，也可用作行为动词，作“必须”、“需要”讲。作为情态动词，need也只用于否定句和疑问句。如：He neednt worry about it.Need I collect the books myself?作为行为

7、动词，其后接的不定式要加to。如: I want to go to the dentist, but you need not go with me. 我要去看牙科医生，但你不必跟我一起去。( need作情态动词) He needs to buy a new pair of shoes. 他需要买一双新鞋子。(need作实义动词)以need作情态动词提问，其答语如果是肯定的，须用must; 如果答语是否定的，则用neednt。如：Need we work late today? No, but we must tomorrow.Need I tell Tome at once? No, you

8、 neednt tell her just yet.三. 情态动词表示推测或判断的用法1） 情态动词+动词原形: 表示对现在或将来的情况的推测，此时动词通常为系动词。如: At this moment, our teacher must be correcting our exam papers.You must be hungry after a long walk.She may not be at home. = It is possible that she is not at home.She cant be at home. = It is impossible that she

9、is at home.They should be there right now.2） 情态动词+动词完成时, 即“情态动词+ have + done分词”:表示对过去行为或动作进行推测、评论或判断。 must have done 表示对过去某事的肯定猜测（只用于肯定句）“一定已做 ” cant /couldnt have done 表示对过去的否定推测.“不可能已做” (can/could have done 表推测通常只用于否定句和疑问句)may /might have done 表示对过去的可能推测 “可能已做 ”（may 比 might 表示的可能性在说话人看来稍大些。） 如: Si

10、nce the road is wet, it must have rained last night. He cant have missed the way. I drew him a map. “The dictionary has disappeared. Who could have taken it?” I cant find my keys. I may / might have left them at the school yesterday.四、情态动词在虚拟语气中的用法情态动词用于虚拟语气中表示责备的感情色彩，用法如下：1）should have done表示“本来应该做

11、某事而实际上未做”，而shouldnt have done则表示“本不应该做某事而实际上做了”。如： You should have told me about it earlier. You shouldnt have said such words to your parents.2) ought to have done也表示“本应该”而ought not to have done则意为“本不应该”。如： You ought to have told me about it earlier.You ought not to have said such words to your par

12、ents.3）neednt have done表示“本无必要做某事而实际上做了”。如： You neednt have walked so quickly since time was enough.4）could have done表示“本来有可能而事实上未做到”。如： I could have come on time, but my car broke on the way.情1 May I stop my car here?No, you_.A. cant B. mustnt C. neednt D. dont have to2. Must we clean the house now

13、?No, you _.A. neednt B. may not C. mustnt D. cant3. John his father about his failure in the exam.A. dares not tell B. dares not telling C. dare not tell D. dares not to tell4. You return the book now. You can keep it next week if you like.A. cant B. mustnt C. neednt D. may not5. Johnny, you play wi

14、th the knife, you hurt yourself.A. wont.cant B. mustnt.may C. shouldnt, must D. cant.shouldnt6. The fire spread through the hotel very quickly but everyone get out.A. had to B. would C. could D. was able to7. Would you go out for a walk with me?No, I ._ My girl friend is coming.A. wouldnt B. shall n

15、ot C. wont D. shouldnt8. Man die without water.A. will B. can C. need D. shall9. If he started at 9 0clock, he be there by now.A. need B. shall C. ought to D. must10. I mailed the letter two weeks ago. She_it.A. must receive B. cant receive C. might receive D. must have received11.The professor gave

16、 orders that the experiment before 5:30p.m.A. be finished B. will finish C. must be finished D. would be finished12. There was plenty of time. You_.A. mustnt hurry B. mustnt have hurried C. neednt hurry D. neednt have hurried13. Tom was a diligent boy. He go to school though it was raining hard.A. w

17、as able t o B. could C. couldnt D. wasnt able to 14. _I go back before lunch?No, I dont think you_.A. Need.must B. Do.need to C. Must.have to D. May . ought to15. The teacher do all the exercises, but a pupil_.A. neednt.must B. may not.must C. neednt.neednt D. cant.must16. Would you open the window

18、please ?Yes, I_.A. will B. would C. do D. can17. A lion only attacks a human being when it is hungry.A. should B. can C. will D. shall18. _Must I finish this novel this morning ?_No, you_.A. mustnt B. might not C. dont have to D. cant19. The taxi _ only hold six passengers. It is full. You take the

19、next one.A. may.may B. can.may C. may.can D. must.can20. I a little earlier, but I met a friend of mine on the way.A. may come B. may have come C. could have come D. must have come21. I wish to go home now, I_?A. may B. cant C. must D. do22. He must have finished his homework, _he?A. mustnt B. didnt

20、 C. neednt D. hasnt23. This pen looks like mine, yet it isnt. Whose _it be?A. must B. can C. may D. might24. He didnt do well in the exam. He _hard at his lessons.A. must have worked B. ought to have workedC. would have worked D. has worked25. I wonder how he _that to the teacher.A. dare to say B. d

21、are saying C. not dare say D. dared say26. Mr Baker, a number of students want to see you. _ they wait here or outside?A. Should B. Will C. Shall D. Are27. You_ the trees. Look, it is raining now.A. mustnt have watered B. neednt have wateredC. could have watered D. might have watered28. I _give you

22、an answer tomorrow. I promise!A. must B. will C. may D. shall29. As a soldier, you_ do as the head tells you.A. will B. shall C. may D. ought30. The streets are all dry. It_ during the night.A. cant have rained B. must have rainedC. couldnt rain D. shouldnt have rained31. When _ he leave the hospita

23、l? I asked the doctor.A. will B. shall C. can D. may32. They have not finish the work up to now._Well, they _A. should have B. should C. ought to D. ought have33. Since it is already midnight, we_.A. had better leaving B. ought to have leaveC. should take our leave D. might as well leave34. you_ be

24、happy!A. May B. Can C. Must D. Would35. Must we come tomorrow?_A. No, you cant B. No, you needntC. No, you mustnt D. No, you may not36. You_ miss the lesson, though we_ have it on Thursday.A. mustnt.neednt B. neednt.mustntC. mustnt.mustnt D. neednt.neednt37. To succeed in a difficult task,_.A. one n

25、eeds to work hard B. to work hard is neededC. you need be a hard working person D. to work hard is what one needs38. In case I_, I would try again.A. will fail B. would miss C. should fail D. shall miss39. Some people feel that handguns_.A. should control B. should be controlledC. must be controllin

26、g D. can be control40. _ open the door for you ?A. Would you like that I B. Do you want that I C. Will I D. Shall I41. My son _ the examination, but he wasnt careful enough.A. might be able to pass B. must have passedC. could have passed D. were able to pass42. Isnt it_ strange that the lazy boy pas

27、s the exam?A. should B. has C. might D. would43. We_ the work so early without your help.A. couldnt finish B. cant finishC. couldnt have finished D. cant have finished44. We the manager, but no one _ his telephone number.A. could have called, knew B. could have called, had knownC. could call, had kn

28、own D. could call, knew45. Would you come and join them?I wish I_ . But I am busy at this moment.A. cant B. couldnt C. could D. can46. If Alice _this afternoon, the meeting should be put off.A. would not come B. might not comeC. should not come D. could not come47. I didnt see her in the meeting roo

29、m this morning. She _at the meeting.A. mustnt have spoken B. shouldnt have spokenC. neednt have spoken D. couldnt have spoken48. With so much work on hand, you_ to see the game last night.A. mustnt go B. shouldnt go C. couldnt have gone D. shouldnt have gone49. I thought you like something to read,

30、so I _have brought you some books.A. may B. might C. could D. must50. There was plenty of time. She_.A. mustnt have hurried B. couldnt have hurriedC. must not hurry D. neednt have hurried51. Its still early, you_.A. mustnt hurry B. wouldnt hurryC. may not hurry D. dont have to hurry52. Please open the window,_?A. cant you B. arent you C. do you D. will you53. We_ for her because she never came.A. mustnt have