专四语法第7节--情态助动词

1、专四语法专题第七节：情态助动词 I. 情态助动词考点和知识要点： 情态助动词概述： 情态助动词有 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。 情态助动词知识要点： can / could may / might will, would shall should, ought to must need dare 情态动词 +不定式完成式( have

2、 done) can / could 1) 表示请求和允许 (Permission) 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. ) 2) 表示能力(体力、知识、技能) (Ability) Can you lift this heavy box (体力) Mary can speak thr

3、ee languages(. 知识) Can you skate (技能) 表示“能力”时可与 be able to 互换。 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。 Ill not be able to come this afternoon. 但当表示“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. 3) 表示客观可能性(客观原因形成的能力) (Possibility) T

4、heyve 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 may / might 1) 表示请求和允许 (Permission)。 might 比 may 语气更委婉，而不是过去式。否定回答时可用 cant 或 mustnt ， 表示“不可以，禁止”。 Mig

5、ht/ 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) 表示推测、可能性(不用于疑问句) (Possibility)。 might 不是过去式，它所表示的可能性比 may 小。 He may /might be very busy now. Your mother may /might not know

6、the truth. 3) 用于祈使句，表示祝愿。 May you succeed! 4) may /might.as well 表示“不妨，还是 .的好” ,也可以写作 may /might as well. Since it is raining hard, you may as well stay here. will, would 1) 用于第二人称疑问句中，表示请求、建议等， would 更委婉，不表时态。 Will / Would you pass me the ball, please 2) 表示意愿(Willi ngn ess)、意图(In te ntion )、决心(Dete

7、rmi nation)、承 诺(Promise)等，可用于各种人称。 I will never do that again. 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。 During the vacation, he would visit me every other day. The wound would not heal. 4) 表示估计和猜想。 It would be about ten oclock when sh

8、e left home. shall 1) 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 You shall fail if you don t work hard.(警告) He shall have the book whe n I finish it.允诺) He shall be puni shed.威胁) should, ought to 1）should, ought to表示“应该”，ought to表示义务或责任，比should语气重。 I s

9、hould help her because she is in trouble. 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 You should / ought to go to class right away. Should I open the window 3）表示推测 should , ought to （客观推测）,must（主观推测）。 He must be home by now. （断定他已到家 ） He ought to/should be

10、home by now.（不太肯定） This is where the oil must be.直爽） This is where the oil ought to/should be.（含蓄） Uncertainmight may could can should ought to would will Certainmust must, have to 1）表示必须、必要。 You must come in 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

11、 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。 He play isn t interesting, I really must go now. 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） You re Tom s good friend, so you must know what he l

12、ikes best. Your mother must be waiting for you now. dare, need 1）dare作情态动词用时，常用于疑问句、否定句和条件从句中，过去式形式 为 dared。 How dare you say I m unfair He daren t speak English before such a crowd, dare he If we dared not go there that day， we couldn t get the beautiful flowers. 2) need 作情态动词用时 , 常用于疑问句、 否定句。 在肯定句

13、中一般用 must, have to, ought to, should 代替。 You needn t come so early. Need I finish the work today Yes, you must. / No, you neednt. 3) dare 和 need 作实义动词用时， 有人称、 时态和数的变化。 在肯定句中， dare 后面常接带 to 的不定式。 在疑问句和否定句中， dare 后面可接带 to 或不带 to 的不定式。而 need 后面只能接带 to 的不定式。 I dare to swim across this river. He doesn t

14、dare (to) answer. He needs to finish his homework today. will, would 1) 用于第二人称疑问句中，表示请求、建议等， would 更委婉，不表时态。 Will / Would you pass me the ball, please 2) 表示意愿(Willi ngn ess)、意图(In te ntion )、决心(Determi nation)、承 诺(Promise)等，可用于各种人称。 I will never do that again. They asked him if he would go abroad. 3

15、) 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。 During the vacation, he would visit me every other day. The wound would not heal. 4) 表示估计和猜想。 It would be about ten oclock when she left home. 情态动词 +不定式完成式( have done) 1) can / could + have done 在肯定句中表示“本来可以做而实际上能做某事”，是虚拟语气；在疑问句或否 定

16、句中表示对过去行为的怀疑或不肯定 , 表示推测。 You could have done better, but you didnt try your best. (虚拟语气) He can t have been to that town.(推测) Can he have got the book(推测) 2) may / might +不定式完成式( have done) 表示对过去行为的推测。不能用于疑问句中，没有虚拟语气的用法。 Might 所表示的可能性比 may 小。 He may not have finished the work . If we had taken the o

17、ther road, we might have arrived earlier. 3) must +不定式完成式( have done) 用于肯定句中，表示对过去行为的推测。意为“一定、想必”。其疑问、否 定形式用can，can t代替。参看1) can / could + have done表示推测。 You must have seen the film Titanic. He must have been to Shanghai. 4) should +不定式完成式( have done) 用于肯定句中，表示对过去行为的推测。 He should have finished the w

18、ork by now。 表示“本应该做而实际上没有做某事” ，其否定式表示某种行为本不该发生 却发生了 可以与ought to +不定式完成式(have done)互换。 You ought to / should have helped him. (but you didn t.) She shouldnt have taken away my measuring tape, for I wanted to use it. 5) neednt +不定式完成式( have done) 表示“本来不必做而实际上做了某事”。 You neednt have watered the flowers,

19、 for it is going to rain. 6) will +不定式完成式( have done) 主要用于第二、三人称，表示对已完成的动作或事态的推测。 He will have arrived by now. 情态助动词专四真题模拟题 Among the four sentences below, Sentence expresses the highest degree of possibility. A. It may take a long time to find a solution to the problem. B. It might take a long time

20、 to find a solution to the problem. C. It could take a long time to find a solution to the problem. D. It should take a long time to find a solution to the problem. Which of the following italicized words does NOT indicate willingness A. What will you do when you graduate B. Theywill be home by now.

21、 C. W h o will go with me D. Why will you go there alone When the sentence“Shall I drive you to the airport first” is turned into indirect speech, which of the following is most appropriate He agreed to drive me to the airport first. B. He offered to drive me to the airport first. C. He advised me t

22、o go to the airport first. D. He suggested that I drive to the airport first. Which of the following sentences indicates POSSIBILITY A. The moon cannot always be at the full. B. You cannot smoke inside the building. C. He cannot come today. D. She cannot play the piano. Which of the following senten

23、ces a fact Aren t you tired I A. should have thought C. might have thought Iwent th he only rney in A. must take C. was able to make ere in 19 occasion exactly t B. must have made D. could make 84, and t when I wo days hat was t _ the jou A. Mary and her son must be home by now. B. Careless reading

24、must give poor results. C. He must be working late at the office. DIt s getting late, and I must leave now. Which of the following best explains the meaning of Shall we buy the tickets first A He said that we were going to buy the tickets first B He requested that we buy the tickets first C He sugge

25、sted that we buy the tickets first D He advised us to buy the tickets first Which of the following sentences expresses WILLINGNESS A By now she will be eating dinner B I shall never do that again CMy brother will help you with the luggage D You shall get a promotion The sentence that expresses OFFER

26、 is . A. Ill get some drinks. Whatll you have B. Does she need to book a ticket now C. May I know your name D. Can you return the book next week Nancys gone to work but her cars still there. She by bus. A. must have goneB. should have gone C. ought to have gone D. could have gone you had deonenough

27、for today. B. must have thought D. could have thought Which of the following sentences expresses probability A. You must leave immediately. B. You must be feeling rather tired. C. You must be here by eight oclock. D. You must complete the reading assignment on time. A. must be C. could be B. had bee

28、 n D. must have bee n I told my frie nd. D. can Youborrow my no tes provided you take care of them, A. couldB. shouldC. must I am surprised_ this city is a dull place to live in. that you should thinkB. by what you are thi nking C. that you would thi nkD. with what you were thinking Loud speakers we

29、re fixed in the hall so that everyone_ an opportunity to hear the speech. A. ought to haveB. must have C. may haveD. should have You ark any thi ng about it. It was none of his bus in ess. needn t have told b. needn t telc. mustn t have told d. mustn t tell Heun wisely, but he was at least tryi ng t

30、o do someth ing helpful. a. may have acted b. must have acted c. should act d. would act The meeting s been canceled. Annall that work. a. need to do b. need have c. needn t have doned. needed not to do “ She must be in the dormitory now.”“ No, shebe there. I saw her in the classroom a minute ago. ”

31、 a. mustn t b. can t c. couldn t d. wouldn t He the 8:20bus because he didn t leave home till 8:25. b. ought to have caught d. must not have caught a. couldn t have caught c. shouldn t have caught The door was open” It “ open. I had locked it myself and the key was in my pocket. ” A. can tbeB. must

32、ntbe C. canthave bee n D. must nthave bee n Since the weather is fine wewalk for a while. may B. must C. might as well D. will If your car any atte nti on duri ng the first 12 mon ths , take it to an authorized dealer. A. shall need B. should need C. would need D. will need As it turned out to be a

33、small house party, we so formally. a. need not have dressed upb. must not have dressed up c. did not need to dress upd. must not dress up Which of the following sentence express WILLINGNESS A. By now she will be eating dinner. B. I shall never do that again. C. You shall get a promotion.D. My brothe

34、r will help you with the luggage. Which of the following best explains the meaning of“ Shall we buy the tickets first A. He said that we were going to buy the tickets first. B. He requested that we buy the tickets first. C. He suggested that we buy the tickets first. D. He advised us to buy the tick

35、ets first. Which of the following sentences expresses “ probability ” A. You must leave immediately. B. You must be feeling rather tired. C. You must be here by eight o clock. D. You must complete the reading assignment on time. Someone is knocking at the door. _ it be Venis No, it _ be her； she lef

36、t for New York this morning. A. Can; mustn t B. Might; can tC. May; doesn t D. Can; can t Is there a movie on in the cinema tonight There_ be. I will phone the cinema and find it out. A. might B. should C. can D. could He didn t agree with me at first, but I _ persuade him to sign the agreement late

37、r. A. could B. might C. should D. was able to You _ out last night. I called you several times, but nobody answered. A. must have been B. must be C. might have been D. could be Oh, Jane, you ve broken another glass. You ought _ when you washed it. A. be carefulB. to care C. have caredD. to have been

38、 careful We _ booked. Look, this restaurant is almost empty. A. must haveB. can t haveC. should haveD. needn t have Do you still remember the day when we went to the Great Wall I can t remember it well, but _ A. might it be B. could it have been sometime last autumn C. could it be D. must it have be

39、en s office anyhow. D. must be using I can t get through to the general manager The line is busy. Someone the telephone. A. must use B. uses C. must have been using It is rather cold here. Shall we light a fire No, we _ because things are easy to catch fire. A. won t B. can tC. mustn tD. needn t Listen! The fire engine is roaring. There _ be a