1、第八部分 情态动词一、学习指导情态动词体现说话者的语气和感情，但不能独立存在，需与实义动词原形合成句子的谓语部分。常用的情态动词有以下几组：shall/should(=ought to), will/would, may/might, can/could, must. need 和 dare 被称作半情态动词，因其既可用作情态动词，又可直接作实义动词。也有人将 used to 也归在情态动词一类。下面就逐一讲解它们各自的含义及用途。I. shall/should. should 并非单纯是 shall 的过去式，而是有其独立含义的一个情态动词。1：shall 在初中阶段，我们学习的是 shal
2、l 作为助动词的用法：在第一人称单复数后表将来的意义，在美式英语中已统一使用 will. 如：I shall/will call her up tonight. 我今晚要给她打电话。We shall/will study the chapter in the coming week. 我们将学习这一章节。而在高中阶段，shall 更多地是以情态动词的形式出现，其在句中的含义可归为三类：（1）表示说话人征求对方意见或向对方请示，多用于第一或第三人称疑问句。如：Lets spend the night in the tent, shall we? 让我们在帐篷里过夜，你说好吗？Shall he c
3、ome in? （你）要叫他进来吗？（2）表示说话者警告，命令或威胁的语气。多用于第二或第三人称。如：You shant leave before six. 你六点前不准走。No one shall stop me! 没人能阻拦我！（3）说话者对将来的承诺或预见。如：A1l these things shall be answered for. 一切都会有报应的。I promise that I shall buy you a nice bicycle on birthday.我答应你过生日时送你一辆漂亮的自行车。2：should 表示应该，等同于 ought to. 如：You should
4、 always be on time. 你应该总是准时才对。较为特殊的用法是，它可以在某些句型中表达出说话者惊讶或不理解的语气，译为“居居然” 。如： It is strange that she should work in the same department as her boy friend.她居然同她男友在同一部门工作真是奇怪。II. will/would1：作为助动词，适用于各种人称表将来，would 用于过去将来时。 如：Which place will you visit next? 接下来你要去哪里？Every time he came, he would tell us
5、one or two interesting anecdotes.每次他来，势必会说一两桩轶事给我们们听。2：作为情态动词。will 有“愿意”的意思，而 would 也可用在现在时中，只是语气比 will更婉转客气。如：Will you be my partner? 你愿意做我的搭档吗？Would you like to eat out with me? 想和我出去吃饭吗？The doctor has told him time and again to stop smoking, but he simply wont listen.医生多次劝他戒烟，但他就是不听。I tugged at t
6、he door, but it wouldnt open. 我用力拉门，但门就是不开。III. may/might1：表允许，有“可以”的意思。其中 might 不仅是 may 的过去式，用在当下情形时也可，但语气更为婉转。如：You may sit in the front rows. 你可以坐在前排。- Might I borrow your notebook? 我能借你的笔记本用一下吗？- Of course, you may. 当然可以。（回答是不用 might）- No, you may not. 不可以。注意：（1）can 在口语中也多表示此层意思。只是 may 稍正式些。但 ma
7、y 不用于第二人称疑问句和特殊疑问句，此时只能用 can. 如：May you help me? (X) Can you help me? (/)What may I do for you? (X) What can I do for you? (/)（2）may/might as well 意思近于 had better. 如：Its getting dark, so we may/might as well go back home.天快黑了，我们最好还是回家吧。2：在具体情形下，表猜测，有“可能”的意思。此时 might 的语气更不确定些。如：Dont disturb him. Judg
8、ing from the look on his face, he might/may flare up.别打扰他。从他的表情看，他可能会发火。Wolves might/may not eat for up to two weeks. 狼可能两周都不吃东西。Might it be a true story? 这可能是个真实的故事吗？ （疑问句表猜测不可用 may）3：may 表示祝愿。如：May you succeed! 祝你成功！May all his dreams come true! 愿他的梦想成真！IV. can/could1：表能力，有“能够”的意思，是 be able to 的同义
9、词。如：My cousin can cook French dishes. 我的表弟能做法国菜。Can you hear birds singing in the tree? 你能听见鸟在树上叫吗？注意：can 的过去式 could 表示过去一贯具有的能力，与 was/were able to 一次性得以做成某事，意思有所不同。如：The canoe tipped over, but fortunately we were able to swim across the river.小船翻了，但幸运的是我们得以游过了河。此时的 were able to 等同于 managed to，用 cou
10、ld 则不妥。2：表允许，有“可以，能够”的意思。与 may 类似，过去式 could 用在当下情形，语气更为婉转。Travelers can take pictures everywhere as long as they dont shoot with flash.只要不用闪光灯，游客可以到处拍照。- Could I sit beside you? 我能坐你身边吗？- Yes, you can. 可以。 （答句中不用 could）- No, you cant. 不，不行。3：表猜测，有“可能”的意思。但与 may 不同的是，can/could 表猜测主要用于否定和疑问句，此时 could
11、的语气更不确定。如：Who can it be? 可能是谁？It couldnt be a true story. 这不可能是个真实的故事。can/could 偶尔也用于肯定句，但仅用于从理论上分析其可能性，而非对一具体情形的猜测。如：A sage can sometimes make mistakes. 就连智者也有可能会犯错。V. must1：表义务，有“必须”的意思。语气要重于 should/ought to“应该” 。如：As a soldier, you must obey the orders. 作为一名士兵，你必须服从命令。You mustnt spit in public. 共
12、场所不得吐痰。- Must I wait until they come? 我非得等到他们来吗？- Yes, you must. 是的，你必须等。- No, you neednt/dont need to/dont have to. 不需要等了。注意：如果显然动作是由一客观条件的制约而产生的，则多用 have to“不得不” 。例如：I couldnt get a taxi, so I had to walk home. 因为打不到车，所以不得走回家。2：表不满，有“偏要”的意思。如：The bell must ring when I was busy in the kitchen.当我在厨房
13、學忙忙的时候，门铃偏偏响了。Must you talk so loudly? 你说话非得这么响吗？3：表猜测，有“必定”的意思，是十分肯定的一种猜测。但注意这层意思仅用在肯定句中。He must be a spy, isnt he? 他必定是个间谍，难道不是吗？（此时反意疑问句中用真实时态）Years of hard work must yield fruit. 多年的辛苦工必定会结出果实。VI. 半情态动词 need，意为“需要” ，既可作实义动词，单独做谓语，又可作情态动词后接动词原形。1：肯定句中，need 只做实义动词。如：I need a new watch. 或 I need to
14、 buy a new watch. 我要买块新表。较为特殊的用法是当主语“需要被”时，need 后接动名词主动式或不定式被动力式。如：The flower needs watering. 花儿需要浇水了。 The flower needs to be watered.2：否定或疑问句中，need 的使用更为灵活，既可做实义又可做情态动词，但应当注意体系的统一性。如：You neednt feel embarrassed, need you? （情态动词）你不必感到尴尬，不是吗？You dont need to feel embarrassed, do you? （实义动词）VII. 半情态动词
15、 dare，意为“敢” ，与 need 的用法类似。1：肯定句中 dare 多做实义动词。如：The little girl dares to speak before a large audience. 小女孩敢在大庭广众下发言。例外是 I dare say . “我敢保证”中的 dare，虽在肯定句中却是情态用法。2：否定或疑问句中，dare 可做情态或实义动词，但需注意语法上的统一性。如：He dare not walk a alone. 他不敢一个人走夜路。 （情态用法）= He doesnt dare walk alone at night.注意：有时口语中也会将第二句中的不定式标志
16、 to 省去，这是 dare 的特殊用法。又如：Dared he climb the tree? 他过去敢爬树吗？（情态用法）= Did he dare to climb the tree? (此句中的 to 也可省去，但 dare 仍为实又用法）How dare you .? 你怎敢？情态动词的数量并不多，但同学们在解题时仍会感到困难。问题主要集中在两个方面。（一）情态动词表猜测1事实上，几乎所有的情态动词都可以用来表猜测，只是各自的语气强弱和所适用的场合不同而已，最常见的便是前面提到过的 might/may（表对具体情形的猜测） ，could/can （多用于疑问和否定句中表猜测）及 mu
17、st（仅用于肯定句中，表十分有把握的猜测） 。但也需知道 should 也可表按常理推测所得的结论，译为 “理应，应当” 。如：Having been here dozens of times, you should know this place well.来过这里几十次了，你理应对这个地方相当了解。will 则表示按逻辑推理势必会发生的事。如：All men will die. 所有的人都会死。也算是一种形式的猜测。故有人总结按猜测语气由弱至强，而逐一选用情态动词：might-may-could-can-should(ought to)-would-will-must(=will cert
18、ainly).2：情态动词表猜测时还应注意：对推测时间的表达并非体现在情态动词本身的形式上，如might 与 may 表“可能”时并无时间上的差异，仅是语气强弱罢了。 mght 更不确定些。一切的时态变化均体现在情态动词后的动词形式上。如：一般式 现在式 完成式might/may/must be/do be doing have done 如有具体过去时间，则为对过去的猜测might not/may notcouldnt/cant如：He cant have finished his homework, has he? 他不可能已经完成了作业，难道不是吗？3：对猜测的否定有两种，一是部分否定，
19、 “可能不”用 might/may not；另一种为完全否定，“不可能”could not/can not.（二）情态动词在虚拟语气中的应用1：某些情态动词的形式上打上了虚拟语气的烙印，即使没有前后说明，也应明白其包含的意思。如：should have done“应该做而没有做” ，shouldnt have done“不应该做却做了” ，neednt have done“不需要做却做了 ”（注意其与 didnt need to do“不需要做也没做”的酌区别）2：众所周知，虚拟语气的主句中必须用到四个情态，即 might，could ，would，should ，它们的意思各不相同。如对过去
20、的虚拟，主句中常用 might havedone（本有可能做） ，could have done（本有能力做） ，would have done（本来势必会做） ，should have done（本应该做） ，其中 might have done 与情态动词表对过去或完成动作的猜测时所用的形式一模一样，难免会造成概念上的混淆。又如：couldnt have done 究竟是过去不可能做过某事（情态动词表猜测）呢？还是过去本无能力做某事（情态动词的虚拟用法）？建议同学们仔细参考上下文，再下结论。试比较下面两例句：If the driver hadnt stopped the car, he m
21、ight have knocked the old man down, mightnt he?如果当初司机不刹车，他很可能就将那位老人撞倒了，难道不是吗？（显然，此处 might have done 表虚拟）She llooks unhappy; she might have got into trouble, hasnt she?她看上去不高兴。她可能已经遇上麻烦，难道不是吗？（此处 might have done 是对完成式的猜测，故反意疑问句部分用了 hasnt she)二、典型试题分析1. The fire spread through the hotel very quickly,
22、but everyone _ get out. (1997 全国高考)A. had to B. would C. could D. was able to答案为 D. 此处的 was able to 强调在那次事故中得以逃生，与 could 一贯具有的能力不同，故选 D.2. “I stayed at a hotel while in New York.“Oh, did you? You _ with Barbara.“（1998 全国高考）A. could have stayed B. could stay C. would stay D. must have stayed答案为 A此处是考
23、察情态动词在虚拟语气中的运用。 You could have stayed with Barbara.你本是能够住在芭芭拉家的，但事实是你住了旅馆。故选 A.3. “Is John coming by train?“He should, but he _ not. He likes driving his car.“ (2002 全国高考)A. must B. can C. need D. may答案为 D根据意思分析，回答者对约翰的交通方式也只是猜测，并非十分肯定。选 may not 表示他可能不坐火车，因为他喜欢驾驶自己的汽车旅行。4. A left-luggage office is a
24、 place where bags _ be left for a short time, especially at a railway station. (2003 全国高考 )A. should B. can C. must D. will答案选 B行李可以在此处寄放。本句中的 can 表允许，是 can 的基本用法之一。其余选项放入意思均不妥。5. He _ have completed his work; otherwise, he wouldnt be enjoying himself by the seaside. (2005 全国高考)A. should B. must C.
25、could D. need答案为 B. 从句子的后半段推测他此时正在沙滩休闲，显然是完成工作了。选 must have done 表示对已完成动作的推测最佳。6. When he was there, he _ go to that coffee shop at the corner after work every day. (1996 上海高考)A. would B. should C. had better D. might答案选 A. 此处是考察 would 的特殊用法，表示过去经常会做的事，多跟在状语从句之后。used to 也有类似的意思，但强调现已停止了该习惯。7. There
26、was a lot of fun at yesterdays party. You _ come, but why didnt you?(1999 上海高考)A. must have B. should C. need have D. ought to have答案是 D. ought to have done 即 should have done, 表示应该做而未做的事，与后文中的 but why didnt you 相合，故选 D.8. It has been announced that candidates _ remain in their seats until all the p
27、apers have been collected. (2002 上海高考)A. can B. will C. may D. shall答案是 D. 此处是 shall 作为情态动词的常用意，即表示说话者命令的语气。通知所有候选人在交卷前都须坐在原位。故选 D.9. There _ be any difficulty about passing the road test since you have practiced a lot in the driving school. (2005 上海高考)A. mustnt B. shant C. shouldnt D. neednt答案为 C.
28、must 表猜测不用于否定，故 A 错。本句的“既然你在驾驶学校已充分练习，通过路考应该没有什么困难。 ”取 should 表猜测一意， “理应” 。10. “Write to me when you get there.“_.“ (2001 北京春考)A. I must B. I should C. I will D. I can答案是 C. 意为 I will write to you when I get there.11. Mr. Bush is on time for everything. How _ it be that he was late for the opening c
29、eremony? (2001 上上海春考)A. can B. should C. may D. must答案是 A因需填的空格在一疑问句中， “他怎么可能出席开幕式时迟到？” ，故用 can 表猜测。记住：must 与 may iy 不可在疑问句中表猜测。12. According to the local regulations, anyone who intends to get a drivers license _ take an eye test. (2005 上海春考)A. can B. must C. should D. may答案为 B要考驾照必须测视力。这是一规章制度，故用
30、must，加强语气， “一定要”.三、自测练习I. Multiple Choice:l. Im sorry to have troubled you so much. As a matter of fact you _ have come in person.A. mustnt B. neednt C. may not D. could not2. Whenever I was in trouble he _ come to my aid.A. would B. will C. may D. might3. There was no bus service as it was quite la
31、te in the night, so we _ walk home.A. must B. have to C. ought to D. had to4. Look at what youve done. You _ more careful.A. may be B. must be C. should have been D. would have been5. She _ be an American because shes got aFrench passport.A. isnt able to B. doesnt need C. mustn t D. cant6. This coup
32、le _, but they dont any more.A. used to quarrel B. are used to quarrelling C. were used to quarreling D. would quarrel7. You _ do these exercises if you dont want to.A. shouldnt B. mustnt C. neednt D. cant8. You _ now, or youll miss the train.A. ought to have started B. must have startedC. must star
33、t D. need start9. Lets go out for lunch, _ we?A. shall B. will C. should D. may10. Help me to move the table to that corner, _ you?A. shall B. will C. should D. may11. Jack is so wet, he _ in the rain.A. must be caught B. must have been caughtC. can have caught D. may be caught12. Dont believe him;
34、he _ be senous.A. neednt B. mustnt C. shouldnt D. cant13. Hes mad, so you _ better be careful.A had B. have C. would D. might14. Notice in cinema: Exit door _ be locked during performances.A. must B. has C. can D. may15. The car plunged into the river. The driver _ get out but the passengers were dr
35、owned.A. was able to B. could C. might D. would16. He _ him yesterday because he was not at home.A. must not have seen B. could not see C. cant have seen D. should not have seen17. He went on foot, but he _ by bus.A. might go B.could go C. might have gone D. could have gone18. - Has Jane finished ty
36、ping those reports?- No, and they _ an hour ago.A. should have been finished B. should have finishedC. should finish D. ought to have finished19. If you _ wait a moment. Ill go and find our manager.A. can B. should C. will D. must20. - Do you think he will do me a favor?- As far as I know, he is the
37、 last one to help others. He _ be prepared to give you a hand, though.A. might B. must C. can D. should21. Even though Id hurt my leg, I _ swim back to the river bank.A. could B. might C. had to D. was able to22. You _ go to the party if you dont finish your homework first.A. wont B. dont C. oughtnt
38、 D. shant23. - It is rather cold here. Shall we light a fire?- No, we _ because things are easy to catch fire.A. wont B.cant C. mustnt D. neednt24. I _ Professor Jones had taught me this question.A. believe B. think C. wish D. suppose25. The chairman requested that _.A. the members studied the probl
39、em more carefullyB. the problems were more carefully studiedC. the problems could be studied with more careD. the members study the problem more carefully26. I _ it agam.A. would like you to read B. would like that you readC. would like you reading D. would like you read27. If you really want yourse
40、lf to be in good health, you must _ always _ so much.A. not; be smoking B. not; have smokedC. not; to smoke D. be not; smoking28. If I _ you, I _ more attention to Fnglish idioms and phrases.A. was; shall pay B. am; will pay C. would be; would pay D. were; would pay29. - Would you have told him the
41、answer had it been possible?- I would have, but I _ so busy then.A. had been B. were C. was D. would be30. He had an expression of resentment(不高兴), as if Martin _ a fool of him.A. had made B. makes C. made D. would make31. _ the fog, we should have reached our school.A. Because of B. In spite of C.
42、In case of D. But for32. There was a half smile on his face which suggested that he _ happy to have given his life for his country.A. was B. should be C. would be D. were33. We all agreed to her suggestion that we _ to the Great Wall for sightseeing.A. will go B. go C. shall go D. should have gone34
43、. You must be a student, _ you?A. wasnt B. are C. mustnt D. arent35. The young man insisted that he _ nothing wrong and _ free.A. did; set B. had done; shouldbe set C. do; be set D. had done; must be set36. Without your help, I _ the exam last term.A. failed in B. would have failed C. wouldnt pass D
44、. would fail37. _ he come, the problem would be settled.A. Would B. Should C. Shall D. If38. Very loud noise _ make people ill or drive them mad.A. should B. can C. need D. must39. I lost your address, otherwise I _ you long before.A. had visited B. have visited C. would have visited D. should visit
45、40. - Where _?- I got stuck in the heavy traffic, or I _ here earlier.A. did you go; had arrived B. are you; would comeC. were you; would come D. have you been; would have been41. Will you answer the phone? It _ be your mother.A. might B. will C. shall D. need42. _ she rest in peace!A. May B. Can C.
46、 Would D. Might43. _ you park your car on the side walk in your country?A. May B. Can C. Would D. Might44. The boss had one strict rule. He said that all the workers _ come to work on time.A. must B. could C. might D. would45. I got lost and _ ask a policeman the way.A. could B. might C. must D. had
47、 to46. The bus _ at 9:30, but it didnt turn up.A. must have arrived B. may have arrivedC. neednt have arrived D. ought to have arrived47. He didnt agree with me at first, but I _ persuade him later.A. was able to B. could C. can D. might48. - Could I use your phone?- Yes, of course you _.A. could B. can C. must D. might49. When I was ten, I _ watch most TV programs if I asked my parents first.A. might B. could C. should D. had to50. You were stupid to try climbing up there. You _ yourself.A. might have killed B. should have killed C. must have killed D.cant h
