| dadadada |
2005-09-04 11:30 |
考点说明
1.情态动词表示推测现在、过去和将来。
2.情态动词的否定用法和否定意义,表现在对话的简略答语中和反意问句中。
3.“should/need+现在完成”时的意思及用法,即could/might是过去时形式,但表示现在时的含义。
4.情态动词的时态变化及其无时态差别的用法。
5.情态动词在虚拟语气中的用法。
点内热点
知识点综述
1.can,could,be able to表示“能力”。
(1)can/could表示“能力”,can表示现在或将来的“能力”,could表示过去的“能力”。
例如:She can swim.
He could swim when he was young.
(2)be able to有人称和时态变化,可以表示现在和过去的“能力”,也可表示将来的“能力”,结构为:will be able to。
例如:When the fog lifts,we will be able to see where we are.
注意:一般说来,can/could表示“主观方面的能力”或总的习惯性的“能力”,be able to 表示“客观方面的能力”或“特定的某一(种)能力”。
例如:He said he could swim across the lake.
2.can/could表示“允许”、“许可”。
(1)can用于表现在或将来,could用于表过去,主要用在间接引语中。
例如:You can use my bike now/tomorrow.
He said that I could park here.
(2)could可以表示客气的询问是否“允许”,此时无过去时的含义。回答时用can/can't,不用could/couldn't。
例如:—Could I smoke here?
—Yes,you can. (No,you can't.)
3.may/might表示“可能”,may比might的可能性大。
例如:—Why isn't John in class?
—He may be sick.(生病的可能性较大)
—He might be sick.(生病的可能性较小)
4.may/might表示“允许”。
(1)may/might表示“允许”,may用于现在时或将来时,might常用在间接引语中,表示过去时。
例如:He says we may leave.
He said we might leave.
(2)may和might用于疑问句中,都可以用来询问是否“允许”,但might比may更客气,意思更不肯定,无过去时态的含义。
例如:—May/Might I use your eraser?
—Yes,you can/may.
—No,you mustn't.(不能说:No,you can't.)
5.must表示命令或建议,无时态形式的变化。
例如:She said they must do as they were told.
6.must表示推测。
(1)must表示对目前发生的动作作肯定推测,结构为:must+do sth.;表示对过去发生的动作作肯定推测,结构为:must+have+p.p.。
例如:The light is still on,he must be in the office.
I was told his mother was ill,so he must have gone to the hospital.
(2)作否定推测时,不能用mustn't,要用can't或couldn't。
例如:He can't finish his work because he doesn't come here.
7.must,have to的区别。
(1)must表示说话人主观认为“必须”做某事,have to表示由于某种外界(客观)原因而“必须”、“不得不”做某事,must表一件重要的或紧要的事“必须”做,have to表经常的或习惯的事“必须”做。
例如:You must clean your own boots.
You will have to clean your own boots when you join the army.
I must be at the station at ten. My mother's train will arrive.
I have to be at my office every day.
(2)must的时态为现在和过去,而have to有各种形式。
must可表示推测,而have to不可表示推测;must的否定用法依句情而定,而 have to的否定式只能借助于助动词do/did构成。
例如:You mustn't tell him the news.
You don't have to tell him the news.
8.should和ought to的区别。
(1)should和oughtto用于肯定句中作“应该”解,都表示现在的“义务、责任”,只是前者比后者语气轻。
例如;You should/ought to study hard.
(2)用于问句中表示提出或征求建议或提出劝告。
例如:Should I open the door?
9.need和dare的比较。
(1)need为情态动词,无人称和时态的变化,后接动词原形,need为实意动词时,有人称和时态的变化,后接带to的不定式。
例如:I don't suppose he need wear a coat.
It needs to be done carefully.
(2)dare用作情态动词,无人称变化,只有过去式变化(dared);用作实意动词有人称和时态的变化,后接带to的不定式。
例如:I'm surprised that he dares to speak to his father like that.
10.shall,will和would的比较。
(1)shall用于疑问句中主语为第一、三人称时,表示征求建议或询问。用于陈述肯定句中,主语为第二、三人称时,表示“许诺”,“威胁”和“强烈的意志”。
(2)will用于疑问句中,主语常为第二人称时,表示“邀请”、“建议”或“请求”。用于陈述句中,主语为各人称,表示“意志”、“命令”,在否定句中表示“拒绝”。
例如:Will/Would you have a drink?
He won't listen to me.
11.“may/might+现在完成时”,表示推测,意为“也许”,“可能”。may比might的可能性大,主句中的谓语动词为过去时,从句谓语动词只能用might,此时与may可能性大小相同,只是时态上的差别。
例如:I can't find my sunglasses.I may/might have left them at the restaurant.
注意:“might+现在完成时”表示对并未发生的动作加以猜测,这种句子类似条件句。
例如:Perhaps we should have taken the other road.It might have been quicker.(=If we had taken the other road,we might have arrived earlier.)(虚拟语气现象)
12.“should/ought to+have done sth.”表示应该发生或完成而实际上并未发生或完成,意为“本应该……”。
例如:The flowers died.You should/ought to have watered them.
13.“needn't+完成时”表示过去某动作已经发生,但无须发生,意为“本不必……”。
例如:It's not very far,so we needn't have taken a taxi.
14.“would+现在完成”主要用于条件句中(虚拟语气)。
例如:If you have come earlier,you would have seen her.
15.“情态动词+be+v.-ing”形式:此结构表示推测某动作现在是否正在进行。
例如:She may be washing her clothes.她可能正在洗衣服。
He must be studying in the library.他一定正在图书馆里学习。
They shouldn't be watching TV now.他们不该在看电视。
范例分析
【例1】You________ return the book now.You can keep it till next week if you like.
A. can't B. musn't C.needn't D. may not
分析 needn't表示说话人的劝告即主观上认为没有必要,这与题干中的“if you like”含义一致。don't have to“没有必要”表示客观上或习惯上。mustn't意为“禁止做……”,“不许……”,与句意不符。may not意为“不得……”(=must not)。选C。
【例2】You _______ have the book as soon as I finished.
A. will B. shall C. must D. might
分析 shall在陈述句中,主语为第二、三人称,表示说话人的“许诺”。其他情态动词无此意思。选B。
【例3】—Could he have been arrested by the police?
—Yes,he_______.
A. might B. might have C. might have been D. could
分析 在回答“情态动词+完成时态”的句子时,答语里要在情态动词后加have,如果是被动语态,答语里还要保留been动词。即当问句中谓动里有多个助动词,若各助动词的语法功能各不相同时,在简略答语中保留所有功能不同的助动词。选C。
【例4】The boy must be in the classroom,_______he?
A. mustn't B. doesn't C. hasn't D. isn't
分析 must作为表推测的用法时,反意问句的构成取决于must后动词不定式的构成和句中的时间状语,选D.
【例5】I thought that smoking in the forest_______ a fire.
A. might lead to B. might have led to
C. may lead to D. may have led to
分析 由thought过去时态知,从句中的情态动词也应用过去时态形式,故排除C项和D项。might在此表推测,语气上与may相同,是may的过去式,“在森林中吸烟可能引起火灾”无时间上的差别,表示一般时间概念上的一种可能性,故排除B项,因为B项表示对过去情况的推测。选A。
【例6】With not all the work finished,he_______the party last night.
A. needn't have gone to B. wouldn't have gone
C. shouldn't have gone to D. couldn't have gone to
分析 “needn't have gone to"表示“本不必……”;“wouldn't have gone to”只用于表示与过去客观事实相反的虚拟语气句;“couldn't have gone to”表推测,意为“肯定没……”;“shouldn't have gone to”意为“本不该做……而做了”。依据题意知C项最切近题意。选C。
热点题展示
1. He is wet to the skin. He ________ in the rain.
A. must have caught B. must have been caught
C. must catch D. must be caught
2. Don't be worried. The news ________ be true.
A. does not B. mustn't C. can't D. shall not
3. Mother ________ us stories when we were young.
A. was used to tell B. is used to telling
C. used to tell D. used to telling
4. I wonder why it's so dark. There ________ be a heavy rain coming.
A. shall B. may C. can D. would
5. The meeting has already begun. You ________ minutes ago.
A. should come B. ought to come C. must have come D. ought to have come
6. Two men want to see you. Where ________ they wait, outside or here?
A. shall B. will C. do D. would
7. —Could I borrow your bike?
—Yes, of course you________.
A. can B. should C. will D. might
8. —________ I go at once?
—No. I don't think you________.
A. Must, have to B. Must, ought to C. Can, must D. May, ought to
9. There are so many people in the street that I ________ get through.
A. couldn't B. needn't C. shouldn't D. can't
10. —________ you jump down from the top of the wall?
—No, I ________ do it. It's too high.
A. Could, can't B. Shall, wouldn't C. Dare, daren't D. Will, wouldn't
11. He worked hard but ________ pass the exams.
A. would B. can't C. was able to D. couldn't
12. —We expected you yesterday.
—I'm sorry I ________ you to say that I ________ here until today.
A. should have called, couldn't be B. must have called,can't be
C. would be calling, wouldn't be D. could have been called, mightn't be
13. —Do you think it will rain?
—I don't know. It________.
A. will B. might C. ought to D. can
14. The classroom is empty. I think they ________ to the library, haven't they?
A. should have gone B. ought have gone C. must have gone D. must go
15. She doesn't answer the phone. She ________ be asleep.
A. should. B. must C. might D. ought to
考题精解
【例1】I didn't hear the phone. I_______asleep.
A. must be B. must have been C. should be D. should have been
分析 must be表示对现在情况的推测,should be表示对现在情况的判断,均与“didn't”过去情况矛盾,故排除A、C项。must have been表示对过去情况的推测,意为“那时,肯定/一定……”。should have been意为“本应该……而没有”,按此意理解,应表述“我听到了电话”,显然与原题矛盾,故排除D项。选B。
【例2】A computer _______ think for itself,it must be told what to do.
A. can't B. couldn't C. may not D. might not
分析 can't表示“能力”,指主语现在具有的能力,而couldn't表示“能力”,指主语过去具有的能力。当说明某物本身所具有某种性质时,只能用一般现在时态来表达,显然B项与之时态概念不符,排除。may not和might not无“能力”的意思,排除。can't和couldn't也可表示推测,是must表示推测的否定结构和过去时态用法。从后一句话知,此题不具有表推测的意思,故这种解题的思考方式错。选A。
【例3】—Could I borrow your dictionary?
—Yes,Of course you________.
A. might B. will C. can D.should
分析 could表示更为委婉地提出请求,表示现在时态的概念,可以用can,may,might代替。回答这一类问句时,情态动词只能用can或may(may较正式,不常用),不能用could或might。will表示“意愿”,should表示“应该”与题意不符。选C。
【例4】Tom ought not to ________ me your secret,but he meant no harm.
A. have told B. tell C. be telling D. having told
分析 本题既考查了情态动词的用法,又考查了动词的时态。ought to中的“to”是不定式符号,后要接动词原形,故排除D项。but分句中的“meant no harm”明确显示了Tom已把“your secret”告诉了me且含有“不该这样做”的意思。显然应接完成式形式。故选A项。
【例5】—What's all that noise upstairs? It sounds like a herd of sheep.
—The children ________ some kind of game.
A. may play B. must play C. may be playing D. must be playing
分析 此题考查may和must后接动词原形和动词进行式表示推测的语言现象。解题时抓住题干中的“upstairs(地点)”sounds(时间)”,“a herd(群)of sheep(玩的内容)”这些关键性词组,即可知描述的是对“此情此景”作出的判断,即用“情态动词+be+v-ing”形式。选C。
【例6】—Will you stay for lunch?
—Sorry,________.Brother is coming to see me.(全国·1999)
A. I mustn't B. I can't C. I needn't D. I won't
分析 解题的关键是答语中的后一句话。它说明了不能留下来吃饭的原因。而A项意为“禁止”,“不允许”,C项意为“不必”;D项意为“不愿”。均与题意不符。选B。
【例7】—When can I come for the phones? I need them tomorrow afternoon.
—They________be ready by 12:00.(全国·1998)
A. can B. should C. might D. need
分析 此题考查情态动词表推测的用法。先排除A项,因为can在表推测的用法中只用于否定句和疑问句中;D项need不表示推测,故也排除;C项 might表示推测意为“可能”,“也许”,语气很弱,与题意不符。选B。
【例8】The fire spread through the hotel very quickly but everyone________get out.(全国·1997)
A. had to B. would C. was able to D. could
分析 A项和B项显然与题意不符。could是can的过去式,表示主语的主观能力。could也可指主语过去所具有的暂时性能力,显然与题意不符。be able to表示客观能力所为,而由宾馆的特殊设施所决定,这是客观能力。选C。
基础巩固训练
16. The tiger ________ hibernate in winter.
A. don't need B. doesn't need to C. needs not to D. need not
17. —You ought to have come earlier.
—Yes, I ________. But the traffic was heavy.
A. ought to B. should C. must have D. should have
18. If you smoke in bed, it ________ be dangerous.
A. might B. can C. has to D. ought to
19. I tried to stop him from smoking, but he just ________listen.
A. won't B. wouldn't C. may not D. might not
20. —________ I carry the box for you?
—No, thanks. I can manage it.
A. Will B. May C. Shall D. Should
21. —John must have lost his way, for he hasn't arrived yet.
—No, he_______ his way. He has got a map with him.
A. must not have lost B. shouldn't have lost
C. can't have lost D. can't be lost
22. You_______ walk for miles through the forest without meeting anyone.
A. may B. must C. need D. should
23. —Need I start now?
—Yes, you_______.
A. need B. must C. do D. can
24. He_______ his parents that he has failed in the exam.
A. dares not tell B. dares not telling
C. dare not tell D. dares not to tell
25. It's time for class. You _______ leave now.
A. won't B. shan't C. will D. shall
26. After her husband's death, the old lady _______sit by the window sadly.
A. would B. could C. was used to D. might
27. —Shall I go home now?
—No, you_______. Your work hasn't been finished.
A. needn't B. mustn't C. won't D. wouldn't
28. —This job ought to have been finished hours ago.
—Sorry, I know it_______.
A. should have done B. must have been
C. ought to be finished D. should have been
29. The boy stood there without _______ a word.
A. dare to say B. daring to say C. dared to say D. dare say
30. —What has happened to us?
—I don't know. We _______ lost.
A. could got B. might got C. can have got D. may have got
能力迁移训练
31. —I stayed at a hotel while in New York.
—Oh, did you? You _______ with Barbara. (全国·1998)
A. could have stayed B. could stay C. would stay D. must have stayed
32. This room needs painting. _______ paint it for you?
A. Will I B. Should I C. Must I D. Shall I
33. —Was it the new teacher who walked by?
A. It must be B. It must have been C. He must be D. This must have been
34. Sir, you _______ be sitting in this waiting room. It is for women and children only.
A. oughtn't to B. can't C. won't D. needn't
35. You _______ return the book now. You _______ keep till next week if you like.
A. needn't,can B. mustn't,may C. can't,can D. may not,must
36. I got up early this morning, but I _______ so because I _______ work on Sundays.
A. mustn't have done, mustn't B. needn't have done, needn't
C. didn't need to do, didn't D. can't have done, can't
37. You must have studied English for many years, _______ you?
A. mustn't B. didn't C. aren't D. haven't
38. —How do you like the food there?
—Oh, very good! We _______ a better hotel.
A. can't find B. won't find C. mustn't have found D. couldn't have found
39. There _______ no trouble in finishing the work on time.
A. ought to have B. should to be C. mustn't be D. ought to be
40. Last night, he hurt his foot, but at last he _______ get home safely.
A. could B. need C. was able to D. dare
41. You _______ read the paper if you don't want to.
A. haven't B. can't C. mustn't D. needn't
42. —May I sit here?
—_______.
A. No, you mustn't B. No, you may not C. No, you dare not D. No, you needn't
43. There used to be a tower on that hill,_______?
A. didn't there B. usedn't it C. used there D. didn't it
44. She _______ run very fast when she was young.
A. must B. can't C. must be able to D. must have been able to
45. They left yesterday. They _______there by now.
A. need arrive B. should arrive
C. can have arrived D. need have arrived
46. —Did you blame Jim for his mistake?
—Yes, but I _______ it.
A. shouldn't have done B. shouldn't do
C. should have done D. should do
47. It's nearly seven o'cloek. Jack _______ be here at any moment. (全国·1995)
A. must B. need C. should D. can
48. Janny _______ have kept her word. I wonder why she changed her mind. (全国·1991)
A. must B. should C. need D. would
49. Susan _______ written a report like this. (上海市·1995)
A. can have B. mustn't have C. can't have D. ought to not have
50. We _______ last night, but we went to the concert instead. (全国·1992)
A. must have studied B. might study
C. should have studied D. would study
参考答案
1—5 B C C B D 6—10 A A A A C 11—15 D A B C B 16—20 D A B B B
21—25 C A B C A 26—30 A B D B D 31—35 A C B A A 36—40 B D A D C
41—45 D A A D B 46—50 A C B C C |
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