模塊四 語法專練：情態(tài)動詞
【考點透視】
從近幾年的高考試題來看，情態(tài)動詞是一大熱點。每年單項填空題必考一題，通常從三個方面來考查考生對情態(tài)動詞的運用：一是情態(tài)動詞本身所表達的意義，如表示禁止、命令、威脅、許諾等意義；can, may, might, need, shall, should等的用法。二是“情態(tài)動詞+have done”表示推測。三是情態(tài)動詞后面省略形式的用法區(qū)別，如I could (=I could do），I could have (=I could have done)的區(qū)別。
（一）can和could的用法
1．表示能力或客觀可能性，還可以表示請求和允許。例如：
Can you finish this work tonight?
一Can I go now? 一Yes，you can.
2．could也可表示請求，是委婉的語氣，主要用于疑問句，不可用于肯定句，答語應用can，即could不能用于現在時態(tài)的簡略答語中。例如：
一Could I come to see you tomorrow?
一Yes，you can. (否定答語可用No，I’m afraid not)。
3．表示驚異、懷疑、不相信的態(tài)度。(主要用在否定句、疑問句或驚嘆句中)
Can this be true?
4．“can (could) + have + 過去分詞”的疑問或否定形式表示對過去發(fā)生的行為懷疑或不肯定。例如：
He cannot have been to that town.
（二）may和might的用法
1．表示請求、可以與允許的情況，might比may的語氣更加委婉。may的否定式為may not，但表示“不可以、禁止”答意思時常用mustn’t代替may not。例如：
一May I take the book out of the reading-room?
一Yes, you may. (No, you mustn’t. / No, you may not. / No, you’d better not.)
2．“may / might + have + v-ed”結構表示對過去行為的推測，含有“想必、也許會”的意思。
She may／might have missed the train.
（三）must和have to的用法
1．must的否定式有兩個：mustn’t表示“禁止”；needn’t/ don’t have to是一般疑問句的否定答復。例如：
一Must we hand in our exercise books today?
一No，you needn’t.
2．“must have done”意思是“過去一定做了”；其否定式“can’t/ mustn’t have done”意思是“(過去)不可能做了”；而“needn’t have done”意思是“(過去)沒必要做”。
3．must與have to的區(qū)別；二者含義很相似，兩者往往可以互換使用，但have to有各種形式，隨have的變化而定。must與have to有下列幾點不同：
（1）must表示的是說話人的主觀看法，而have to則往往強調客觀需要。
（2）must一般只表示現在，而have to則有更多的時態(tài)形式。
（3）詢問對方的意愿時應用must。
（4）表示理論上的論斷和自然法則的必然性時，應用must。例如：
We must believe that only socialism can save China.
（四）dare和need的用法
1．need表示“需要”或“必須”，作情態(tài)動詞時，僅用于否定句或疑問句中，在肯定句中一般用must，have to，ought to或should代替。例如：
―Need I finish the work? ―Yes, you must.
注意：needn’t have done表示“本來不必做某事而實際上做了某事”。
2．dare做情態(tài)動詞時，主要用于疑問句、否定句和條件從句中，一般不用肯定句中。例如：
How dare you say I’m unfair?
3．dare和need常用作實義動詞，有時態(tài)、人稱和數的變化。所不同的是，作實義動詞時，在肯定句中，后面通常接帶to的不定式，在否定和疑問句中，后面可接帶to或不帶to的不定式。
（五）shall和should的用法
1．shall常用于第一、第三人稱。若用于其他人稱時，則表示說話人給對方的“命令、警告、允諾或威脅”。
2．shall用于條約、規(guī)章、法令等文件中，表示義務或規(guī)定，一般用第三人稱，意為“一定”。
3．shall用于if/ when引導的從句中，表示將來的可能性，語氣較強，意為“將”。例如：
When I shall see him, I will give him your message.
4．should常表示“驚異、贊嘆、不滿”等情緒。主語從句中謂語動詞要用“should＋動詞原形”。
5．should have done意為“應該做而未做”；shouldn’t have done意為“不應該做而做了”。
6．should表示勸告、建議、命令。同義詞未ought to。
（六）will和would的用法
1．表示請求、建議等，would比will委婉客氣。
2．表示意志、愿望和決心。
3．will be和will have done的結構均表示推測，主要用于第二、三人稱。前者表示對目前情況的推測，后者表示對已經完成的動作或事態(tài)的推測。
This will be the book you want.
The guests would have arrived by that time.
4．would可表示過去反復發(fā)生的動作或某種傾向。would表過去習慣時used to正式，并沒有“現已無此習慣”的含義。
（七）ought to的用法
1．ought to表示應該
2．ought to表示推測
3．ought to have done表示過去應做某事而實際未做。（這時ought to和should可以互換）
（八）used to，had better，would rather的用法
1．used to表示過去的習慣動作或狀態(tài)，現在已不存在，在間接引語中，其形式可不變。在疑問句、否定句、否定疑問句或強調句中，可有兩種形式。如：
Did you use to go to the same school as your brother?
Used you to go to the same school as your brother?
I usedn’t to go there.
I didn’t use to go there.
She used to be very fat, didn’t she? / use(d)n’t she?
2．had better意為“最好”，后接不帶to的不定式。
3．would rather意為“寧愿”，后接不帶to的不定式。由于would rather表示選擇，因而后可接than。如：
I would rather work on a farm than in a factory.
I would rather watch TV than go to see the film.
I would rather lose a dozen cherry trees than you should tell me one lie.
【題例精析】
【例1】 -Didn’t they come to the party last week?
-Yes. They didn’t want to come with us at first, but then we ____ persuade them.
A. would B. could
C. were able to D. had to
【易錯點悟】解答該題的關鍵在于區(qū)別can 與be able to 表示“能力”的用法。
【要點精析】根據上下文語境及講話人語氣，選項動作表示經過努力才完成的。在這種語氣的肯定句和疑問句中，常用be able to，在否定句中可用can。
【答案】C
【例2】 You ____ pay too much attention to your reading skill, as it is so important. （2007北京四中交流卷）
A. can’t B. should
C. must D. needn’t
【易錯點悟】解答該題的關鍵是對“can’t...too...”固定短語的理解。
【要點精析】根據句子意義：無論怎么注意你的閱讀技巧都不過分。同時句中由于有了too...to結構，只有can’t可以與它構成固定短語，有此含義。其它選項無此意。
【答案】A
【專項檢測】
1. I promised to get there before 5 o’clock, but now the rain is pouring down. They ______ for me impatiently.
A. may wait B. ought to wait
C. could wait D. must be waiting
2. He was very brave. Even though she’d hurt her leg, she ________ go back alone.
A. could B. might
C. have to D. was able to
3. You ________ pay too much attention to your reading skill, as it is so important.
A. cannot B. should
C. must D. needn’t
4. I’ve tried several times, but the car just _______.
A. doesn’t start B. wouldn’t start
C. won’t start D. didn’t start
5. Always the old lady ______ sit for hours doing nothing at all.
A. was used to B. would
C. used to D. should
6. There used to be a small school,___________?
A. was there B. wasn’t it
C. usedn’t there D. usedn’t it
7. Our house is on the top of the hill, so in summer the wind _____ be pretty cold.
A. must B. can
C. ought to D. need
8. Haven’t I told you that you __________ have the answer tomorrow morning?
A. will B. shall
C. should D. would
9. I’m surprised that he _______ in the match.
A. should fail B. should have failed
C. would have failed D. may have failed
10. Better go to see my sick colleague right now, ________I?
A. hadn’t B. didn’t
C. don’t D. won’t
11. Sir, you ______ be hunting deer here, for they are preserved by the government.
A. oughtn’t to B. can’t
C. won’t D. needn’t
12. Sorry I’m late. I ______ have turned off the alarm clock and gone back to sleep again.
A. might B. should
C. can D. will
13. - There were already five people in the car, but they managed to take me as well.
- It __________ a comfortable journey.
A. can’t B. shouldn’t be
C. must have been D. couldn’t have been
14. To be on the safe side, we should fill up the tank now, because we ______ run out of gas on the way.
A. can B. would
C. might D. should
15. ____ three people who travel together, there _____ be at least one who ____ be my teacher.
A. Between; can; will B. In; should; could
C. Among; will; may D. Of; must; can
16. -Could you lend me that book you ______ me about when I telephoned you?
-No, I am sorry, I can’t. I gave it to a friend.
A. were telling B. would tell
C. had told D. had been telling
17. -We need a person badly to think up such an idea.
-_______ the new comer have a try?
A. Shall B. May
C. Should D. Need
18. We ________ so tired. We’ve only been to a party.
A. mustn’t have felt B. wouldn’t have felt
C. shouldn’t have felt D. couldn’t have felt
19. Professor Smith, many students want to see you. __________ they wait here or outside?
A. Do B. Shall
C. Will D. Would
20. -How about paying a visit to Mr. Richardson, our former history teacher?
-Good idea. I will e-mail him today so he _____know _________ to expect us.
A. shall; why B. may; when
C. would; why D. will; how
21. -I went to work on foot yesterday, though it _________ cats and dogs.
-You __________ by bus. It was likely to get a cold.
A. is raining; must have gone B. rained; would go
C. was mining; should have gone D. have rained; could have gone
22. You ______ pay too much attention to your reading skill, as it is so important.
A. cannot B. should
C. must D. needn’t
23. I told Sally to fix him up with this job, but perhaps I _________ it out for her.
A. had to write B. must have written
C. should have written D. ought to write
24. My sister met him at the Grand Theatre yesterday afternoon, so he ________ your lecture.
A. couldn’t have attended B. needn’t have attended
C. mustn’t have attended D. shouldn’t have attended
25. Research findings show we spend about two hours dreaming every night, no matter what we ________ during the day.
A. should have done B. would have done
C. may have done D. must have done
26. -Is there any flight to Tokyo today?
- I think there _____, for the weather is too bad.
A. mustn’t be B. mightn’t be
C. needn’t be D. can’t be
27. -I’m told that John had another car accident this morning.
- I believe not. He _____ so careless.
A. shouldn’t have been B. wouldn’t have been
C. couldn’t have been D. mustn’t have been
28. It was playing computer games that cost the boy a lot of time that he __________ doing his lessons.
A. might have spent B. ought to have spent
C. must have spent D. could have spent
29. -I didn’t know you were good friends.
-You _______. I have known her since she moved here. You were studying abroad then.
A. may have B. needn’t have
C. couldn’t have D. must have
30. They must have finished the work by the end of last month, __________?
A. mustn’t they B. haven’t they
C. hadn’t they D. didn’t they
31. -I didn’t see her yesterday.
- Of course, you _____, because he had gone for a trip.
A. can’t B. may not have
C. can’t have D. mustn’t have
32. You ________ phone him if you want to, but you _________. He is sure to phone you.
A. may; mustn’t B. have to; needn’t
C. can; doesn’t need D. can; needn’t
33. - She must have gone back to the valley.
- ______, she _____ have. The entrance to it was nowhere to be found.
A. No; mustn’t B. Yes; might
C. Yes; could D. No; couldn’t
34. He _____ full marks, but he was so careless as to make a spelling mistake.
A. must have gained B. can have gained
C. could have gained D. must gain
35. From what you said, she _____ you about it.
A. mustn’t have told B. can’t have told
C. mustn’t tell D. can’t tell
36. - You ought to have made an apology to Tom yesterday evening.
- Yes, I know I _________.
A. ought to B. have to
C. should have D. must have
37. -Is there a fog in the evening?
-There _______ be. I’ll make a phone call to find it out.
A. must B. would
C. will D. might
38. - _______ he help you with the problem?
-Well, though it is very hard, __________ I’ll do what I can to work it out.
A. Shall; but B. Can; and
C. Must; however D. Will; still
39. -How is that, Joan?
-Yeah, it’s from the boss. She _________ first, whether she likes it.
A. shall go B. ought to have gone
C. should go D. must have gone
40. -Would you like to watch the video, in which you can see foreigners making jiaoji during the Spring Festival?
-Sure, it ______ be very interesting.
A. should B. may
C. can D. will
41. -The door was open.
-It _________ open. I had locked it myself and the key was in my pocket.
A. can not be B. must not be
C. can not have been D. must not have been
42. -Where ________ Margaret have put the empty bottles?
-She ________ them away. They must be somewhere.
A. can; can’t have thrown B. must; needn’t
C. must; must have thrown D. cant; must throw
43. -Mum, I climbed to get the Teddy Bear from the top of the shelf.
-My goodness! You _______ yourself. You ______ do that next time.
A. must have hurt; mustn’t B. should have hurt; can’t
C. may have hurt; mustn’t D. might have hurt; won’t be able to
44. -Shall I go and buy more food and drinks for the party?
-No, we have prepared a fridge of those. That _______ be quite enough.
A. can B. may
C. might D. ought to
45. -Hurry up, Michael! It’s ten to three.
-Goodness me! The class_______. I’ll be late again.
A. must begin B. may begin
C. should have begun D. must have begun
46. When he was there, he ____ go to that coffee shop at the street comer after work every day.
A. would B. should
C. had better D. might
47. -I hear you have written a novel.
-Yes, the book ________ be out in a month or so.
A. can B. dare
C. should D. need
48. -How could I thank you enough?
-Don’t mention it. Any other man _________ that.
A. must do B. could do
C. would have done D. should have done
49. -Why aren’t they here yet?
-They ________ the bus.
A. can have missed B. must be late for
C. may have missed D. might be late for
50. Mike _______ come to see me I don’t want to go out in case he comes.
A. can B. must
C. may D. will
51. The thief ________ in from the kitchen window as the door was closed.
A. may climb B. must have climbed
C. could have climbed D. should have climbed
52. -You didn’t invite Bill?
- __________ him too?
A. Must I invite B. Must I have invited
C. Should I invite D. Should I have invited
53. -Why didn’t you attend the lecture yesterday?
-I didn’t think that we _______ on Sundays.
A. should B. ought to have
C. shouldn’t have D. will have to
54. It’s said that there are plenty of hotels in that town. There ______ be any difficulty for you to find somewhere to stay.
A. wouldn’t B. mustn’t
C. shouldn’t D. needn’t
55. -Would you be here to attend the English party this evening?
-Yes, we _________.
A. shall B. would
C. will D. must
56. On Sundays when I was a child, Father and I _______ get up early and go fishing.
A. could B. would
C. might D. should
57. -You’d better keep quiet in class.
-Sometimes I ________ Yesterday, I was very quiet during my English class.
A. would B. do
C. did D. have
58. I lived with my sister this summer and didn’t have to pay rent. So I ______ save most of my salary.
A. could B. would
C. was able to D. should
59. -Look, John’s fallen asleep.
- Oh, he _______ too late last night.
A. might sit up B. should have sat up
C. could sit up D. must have sat up
60. -I posted the letter a week ago.
-Then they __________ the letter by now. It usually takes four days.
A. can have received B. must receive
C. should receive D. ought to have received
61. He used to teach in that university and I _________ ride past it on my way to work.
A. would B. could
C. should D. might
62. -So you have to leave now.
-Yes, I __________.
-How nice it would be if you could stay a bit longer!
A. have to B. ought to
C. do D. have
63. He _______ Shanghai, for I saw him talking with the headmaster a moment ago.
A. must have gone to B. can’t have gone to
C. mustn’t have been to D. can’t have been to
64. From what I learn about their hotel, the service and the weather, they _____ their holiday very much.
A. wouldn’t have enjoyed B. shouldn’t have enjoyed
C. needn’t have enjoyed D. can’t have enjoyed
65. It is not like Jack to be unfriendly, so he _________ you when you called.
A. can’t have seen B. should not have seen
C. must not have seen D. need not have seen
66. -Many people in England love to give advice on weather reporting.
-Yes, but I think the weather office’s computers _________ be more accurate.
A. can B. must
C. ought to D. might
67. -The farmers lived near the high way.
-________ very noisy.
A. It must have been B. They must be
C. That might be D. There must be
68. She is too slow. She ________ pass the test, but she __________ too little.
A. would; knew B. will; knows
C. would; knows D. will; knew
69. -Mary didn’t turn up last time, did she?
-No. She_________. We had changed our plan.
A. shouldn’t have come B. needn’t have to come
C. didn’t need to come D. needn’t have come
70. -They haven’t finished the work up to now.
-Well, they________.
A. should B. should have
C. would D. must have
71. -Shall I go and buy more fruit for the party?
-No, I have already bought 3 baskets. That _________ be enough.
A. can B. ought to
C. may D. might
72. -Why hasn’t the speaker turned up?
-He _________ the flight. I’ll find it out at once.
A. must have missed B. might have missed
C. would have missed D. could have missed
73. I _______ pay Tom a visit, but I am not sure whether I will have time this Sunday.
A. should B. might
C. would D. could
74. -Who is the girl standing over there?
- Well, if you _____ know, her name is Mabel.
A. may B. can
C. must D. shall
75. It has been announced that candidates (考生)________ remain in their seats until all the papers have been collected.
A. can B. will
C. may D. shall
【答案解析】
1．D。must表示推測。根據句意：他們一定正在等我們。所以用must be waiting。
2．D。由even though可知該題意為：她很勇敢，盡管她腿受了傷，她仍然設法獨自回家了。而be able to= manage to，有克服困難設法成功之意。
3．A。cannot / can not / never … too/ enough是一固定搭配，表示“越……越好”、“再……也不過分”。
4．C。考查情態(tài)動詞will的用法。will表示意志、意愿和決心。
5．B。used to和would都有“過去常常”之意，但used to有今昔對比之意，現在再也不這樣了。而would無此用法。
6．C。解此題的關鍵：一、掌握反意疑問句的基本構成，即“前肯后否，前否后肯”。二、了解used to構成的反意疑問句有兩種 （didn’t和usedn’t或usen’t）。三、知道there構成的反意疑問句可由there直接構成，而不用it，所以選擇C。
7．B。can作為情態(tài)動詞，它有一特殊用法，即：表示“有時會”= is sometimes等一般情況。句意為：我們家住山頂，所以有時夏天風會很大。
8．B。shall用于第一、三人稱疑問句時表示征求對方意見或指示。二、三人稱表示說話人的命令、警告、允諾或威脅。
9．B。should意為“竟然”。should have done意為“竟然做了某事”。句意：我很驚訝，他竟然比賽輸了。
10．A。had better是一特殊情態(tài)動詞，它可以寫成better，但無論是had better，還是better，其反意疑問句均由had引導。此外，還遵循“前肯后否”的原則。故選A。
11．A。此題考查情態(tài)動詞ought to的特殊用法。它有表示“道德法律上的必須”之意。此句意為：“先生，您不能在這捕鹿，它們是國家保護動物”。can’t雖有“不能、不準”之意，但它不表示“法律上的不準，道義上的不能”之意，所以排除B。oughtn’t to相當于shouldn’t，但前者語氣更為強烈。won’t表示“不愿、不能”，故排除。needn’t表“不必”，不符合題意。因此排除D。
12．A。can不能用于肯定句中表示推測；will表將來或意愿；should have done意為“本應該……卻未……”。句子表達的是一種對過去的猜測，但可能性不大。
13．D。因對話是對過去事情的推測，所以不能選擇A和B。從上句意義可知：已坐了5個人的小車里再擠一個人一定不是舒服的旅行。答案為D。
14．C。表示對未來可能出現的一種事實的推測，但不是很肯定。
15．D。諺語：“三人行，必有我?guī)煛薄?/p>
16．A。本句意為“你能把那本我給你打電話時你提到的那本書借給我嗎?”，用過去進行時表示對過去情節(jié)，場面的描述。
17．A。shall用于第一、第三人稱表示請求允許，“讓這個新來者試試好嗎?”
18．C。“我們本不該覺得這么累，我們只是參加了個聚會嘛”。have been to是已發(fā)生的事實，“本不該”也是已經存在的狀況。shouldn’t have felt是對已存在的情況的虛擬。shouldn’t“(照常理)本不應該”。
19．B。shall用于第三人稱表示征求許可。
20．B。第一句表示要“拜訪Mr Richardson”；第二個人因此說我給他發(fā)個電子郵件“so (that) he may know”以便于他可以知道“什么時候接我們(期待我們到達)”故選B。
21．C。說話人在主句中使用了過去時態(tài)，因此，用來修飾從句的讓步狀語從句就必定是過去時態(tài)，這樣，就排除了A、D項。should have done表示的是責備對方應該做某事而沒有做，上句已經說明是走路而不是乘車，這樣，就把可would go排除了。
22．A。cannot / can not / never … too / enough是一固定搭配，表示“越……越好”、“再……也不過分”。
23．C。should have done意為“本該干某事”。must have done 意為“準是做了”，不合題意。
24．A。couldn’t have done表示對過去情況的推測，“過去不大可能發(fā)生某事”。B項表示本不必做某事而實際上卻已做了。C項形式錯。D項含有責備批評意味，用于肯定句表示在某時間之前應該完成的事而沒完成，用于否定句表示本不該做的事卻做了。
25．C。根據句意：研究結果表明我們每天都會有2小時在做夢，不管我們白天做了什么。空格處應是表示對白天所做的事情的不肯定的推測。故選C。
25．D。對現在所發(fā)生的事情的否定推測。
27．C。對過去發(fā)生的事情的否定推測。句意：-有人告訴我John今天上午又出車禍了。-我不相信。他不可能那么粗心的。couldn’t have done意為“不可能做了……”。
28．B。句意：就是玩電腦游戲浪費了這個小男孩很多時間，其實他本應當把時間化在學業(yè)上的。ought to have done含有責備批評之意。故答案為B。
29．C。根據此對話的語境，此空應是“你不可能知道，你當時正在國外讀書呢”。you couldn’t have是you couldn’t have known we were friends的簡略形式。該句式表示對過去有把握的否定推測。A項表示“也許知道”；B項表示 “沒必要知道”；D項表示“一定知道”。均不合題意。
30．C。前句是must have +過去分詞時，若前句強調對過去情況的推測（一般都有過去時間狀語），疑問部分的謂語動詞用didn’t + 主語；若前句強調動作的完成，疑問部分的謂語動詞用haven’t/ hasn’t +主語。根據題意，by the end of last month（到上月底為止），表示動作的完成。
31．C。can’t have done 表示對過去發(fā)生的行為不肯定。
32．D�？疾榍閼B(tài)動詞的用法。can表“可以”，needn’t表“不必”。
33．D。句意：- 她一定回到峽谷了。 -不，不可能的。峽谷口找不到的。must have done的否定形式應是：can’t / couldn’t have done。
34．C。could have done意為“本來可以干某事”。
35．B。can’t have done表示對過去發(fā)生的行為的不肯定推測，意為“不可能干過某事”。
36．C。因為題目中由ought to， 其表示過去動作的have在省略回答時不能舍棄。
37．D。might表示把握性小的判斷，意為“也許”。從第二句話說話人要打電話查明，說明他不太清楚，所以用might。must表示有把握的推測．would和will表示推測時把握性僅決于must，意為“大概是……”。
38．D。A、B項因為第二空有并列連詞，排除，C項第一空意思不對，排除；D項第一空表示“將來”的時間，第二空表示“轉折”的含義。
39．A。shall用于第二、三人稱。表示意圖、意志、允諾、命令、命運或必然結果等，此處表示必然結果“她必須先去”。因為后面的從句說明了這種情況：“不管她是不是喜歡”，說明不由她個人決定。選項C表達不了這種意思。
40．A。should用于情態(tài)動詞時可以表示“應該會……，一定……吧”。外國人善于做餃子，他們做餃子的情形一定會很有趣。may只是用于不太確定的推測，不足以表達文中的含義can通常情況下用于疑問句和否定句的推測；will表示將來的情況，而外國人做餃子有趣是一般情況下都會發(fā)生的事情。
41．C。應該注意上句時態(tài)是was，“當時門是開著的”。對過去的事件的否定推測用can not have been。
42．A。must表猜測時，只用于肯定句，而依據They must be somewhere可以判斷答案。
43．C。mustn’t表示“禁止”“絕對不可能”，must表示猜測時，語氣比may更加肯定。
44．D。ought to可以表示“根據外界的事實或條件做出判斷”。can用于推測時常出現在否定句或疑問句中；may和might表示推測的不確定性。
45．D。根據語境，表示有把握的推測，“一定開始上課了”。must + 動詞原形是對現在情況推測，must + have done表示對過去或已發(fā)生的情況的推測，may表示把握性較小的推測。should表示預期，“應該會，一定會……吧”。
46．A。would在這里的意思是“過去經常做某事”，符合語境，而B、C、D均無法使此句合理通順。
47．C。should do的意思是“應該會……，-定……吧”，表示“預期”。
48．C。根據語境，是對過去了的事情表示感謝。情態(tài)動詞 + have done，表示過去。would意為“會，將”。
49．C。根據上下文，他們還沒到這里的原因有可能是他們錯過了汽車。錯過汽車，沒按時到一定是一個過去的動作，所以排除B、D項。can表示推測時常用于否定句和疑問句中。故C項是最佳答案。
50．C。may在此表示對將來的事實進行猜測。
51．B。該句表示對過去的事實進行猜測，用C、D項含義均不對。
52．D。問句中使用了過去時態(tài)，說明動作發(fā)生在“過去”；A、C項表示“現在”或者“將來”，排除。must不能和完成時一起用于疑問句，排除。這里should have done表示應該做某事而沒有做，帶有批評的口氣。
53．A。此句應該用情態(tài)動詞的省略形式，根據意思應用should。
54．C。wouldn’t表“不會”，一般用在過去時態(tài)；mustn’t表“一定不可以，千萬不要”；shouldn’t表“應該不會”；needn’t表“沒必要”。
55．C。首先排除B、D，B表示一種委婉，此時沒必要，D項must語氣不對。shall表單純的將來，而will更好，表示我們將來愿意去。
56．B。“would”表示一種經常性動作，相當于“used to do”，但意思不完全相同。
57．B。do這一助動詞既指代了上文的“keep quiet in class”，又表強調，由于此題設置的是通常狀態(tài)下，故選do，如果用來指過去的動作，則用did。
58．C。would表“會”，should為“應該”，題中could和was able to表“能夠”，符合題意。could為天生所能達到的，而was able to是經努力所能達到的，因此符合“省錢”語境。
59．D。譯為：-看！約翰睡著了。-他一定是昨天晚上熬夜熬得大晚了。must表示有根據的，較為肯定的推測。
60．D。從by now看應該是完成時態(tài)，排除B、C，從It usually takes four days看，應是ought to“應該”，選D。
61．A。would表示過去某一段時間一直重復做的事情。
62．A。have to表示由于客觀原因“不得不”，不能分開；ought to等于should，表示“應該”，do在此句中不能用，不能代替have to。
63．B。can’t have done表示對過去情況的一種比較有把握的判斷。根據下半句：因為一會兒時間前我看見他正和校長談話可判斷：他不可能去了上海。
64．D。can’t have done表示對過去的行為動作的否定，從上文來看“根據我所了解的情況，他們不可能這個假期很快樂”，A項表示“可能已經，該已”，B項表示“過去該做而未做”，C項表示“本來不需做而實際上做了”。
65．A。can’t have done表示對過去事實的推測，意為“肯定沒有……”。should not have done表示不該做而做了；need not have done表示沒必要做而做了；只有must have done，無mustn’t have done形式，mustn’t表禁止。根據句意“不像是Jack不友好”，下句是表推測的，“所以肯定是當你喊他時他沒看到你”。
66．C。此題考查的是情態(tài)動詞的用法。can是 “可以、可能、能夠”的意思；must則是“必須”；might表推測。聯系上下文意，均不可選。而ought to意為“應該”，有更大的事實依據。根據實際情況，the weather office’s computers也確實更準確些，故選C。
67．A。對話中第一句是對過去一件事情的陳述，因此下一句中對過去某種情況的推測應該用must have done句型，故選A。
68．C。前一個空填would，意為“(在過去某個時間)她想要通過考試”，后一空用knows，是在陳述一個事實，意為“但她知道的太少了”。
69．C。shouldn’t have come意為“本不應該來” ，暗含 “她來過了” 的意思，與題意不符；needn’t have to come中need為情態(tài)動詞，傾向于主觀上的“必要”，與題中給出條件“We had changed our plan”不符；didn’t need to come中的need to do表示“(有責任、有義務)做某事”，符合題意。
70．B。should have done意為“本應該做某事(但實際上沒做)”。
71．B。四個選項在句中都不錯，只根據說話人語氣，“已經買了三籃水果”因為不必再買了，說明她認為已經夠了，是一種比較肯定的語氣，而不是猜測語氣。
72．B。在不確定問題答案之前，我們用不肯定的語氣“may”或“might”表推測，又因為推測的動作已經發(fā)生，B項最正確，符合語境。
73．A。選項A表示“在某種意義上應該干……”；選項B、D均表示“過去的一種可能性”。根據題意，只能選A。
74．C。選項A表示允許，意為“可以”；選項B表示能力，意為“能夠”；選項C表示主張，意為“偏偏，偏要”；選項D表示說話者的意圖、命令或決心，意為“必須、一定”。故選C。又如：The car must broke down just as we were going on our holiday.
75．D。shall 用于陳述句第二、第三人稱時，表示說話人的意圖、允諾、警告、命令、決心等，意思是“必須、應該、可以”。句意：據宣布，考生在收卷前必須坐在自己的座位上。