1、第五章情態動詞和虛擬語氣一、情態動詞的語法特征(1)情態動詞不能表示正在發生或已經發生的事情，只表示期待或估計某事的發生。(2)情態動詞除ought 和have 外，后面只能接不帶to 的不定式。(3)情態動詞沒有人稱，數的變化，即情態動詞第三人稱單數不加-s。(4)情態動詞沒有非謂語形式，即沒有不定式、分詞、動名詞等形式。二、虛擬語氣用來表示說話人的主觀愿望或假想，所說的是一個條件，多半不是事實，或與事實相反。高考重點要求：1、情態動詞的基本用法2、情態動詞表示推測的語義差別3、情態動詞后接不定式完成體的不同意義4、虛擬語氣中情態動詞的用法第一節 知識點概述一、情態動詞（一）情態動詞種類1.

2、 can表示體力或腦力方面的“能力”、“技能”或根據客觀條件能做某種動作的“可能性”, 但表示人的體力或智力的具體動作時須用 be able to .He was able to do that without any help.他不需要任何幫助就能完成這項工作。2. may表示“允許，可以”，相當于be allowed to .may或might可和as well連用，表示“建議”，譯為“還是的為好”You may as well keep a certain distance from that mad man. 你們還是離那瘋子遠點為好。You might as well go home

3、 now.你還是現在回家為好。3. must表示“必須”或“應當”、“一定”。4. have to 加動詞原形，表示“不得不”，“必須”，它比must更強調客觀。Tom had to work into the deep night every day to earn a living. 湯姆為了生計每天都得工作到深夜。5. should 表示“勸告”，“建議”或“義務”時，譯作“應當”，或表示“預測”和“可能”。He should take care of his parents as they are old enough not to live on themselves. 由于父母親老

4、了，不能自理，他應當照顧他們。He should be there now. 他應該在那兒。should have done在虛擬語氣中表示“責備或后悔”。6. ought ，只有一種形式，且ought后必須加to，然后跟接動詞原形表示“有義務”或“必要”做某事，譯為“應當，應該”。7. dare 可以用作情態動詞，后面跟不帶to的動詞不定式，這主要用于否定句中，它本身可有現在時第三人稱單數，詞尾加s，它還可以有ing分詞形式(daring)和過去式及ed分詞形式(dared)。（二）情態動詞在一般時否定句中的用法can't(cannot) 表示“不可能”， may not 表示“不可

5、以”， mustn't(must not) 表示“一定不要”，“不許可”，needn't (need not) 表示“不必”，dare not 動詞原形表示“不敢”。He can't finish his essay by this time. 現在他不可能寫完論文。He may not sleep now. 他或許現在沒在睡覺。You mustn't criticize her in that way. 你不應那樣批評她。You needn't come tomorrow. 你明天沒必要來了。He dared not meet his fianc

6、33;e. 他不敢見女朋友。（三）can，may，must三者用法比較can，may，must是三個最重要的情態動詞，其基本句型如下：肯定句：主語+can，may，must +動詞原形否定句：主語+can，may，must +not +動詞原形疑問句：Can，May，Must +主語+動詞原形1. can，may，must的肯定句You may eat lunch，but you must wash your hands.你可以吃飯，但是你必須洗手。（1）cana.表示能力；能，會She can run fast，but I can't.她很會跑，但是我不會。b.表示可能；能夠I ca

7、n get there in ten minutes.我十分鐘之后就可以到那兒。（表示一種可能性）c.表示允許；許可You can use this dictionary.你可以用這本字典。d.can和be able to比較can只有現在式和過去式，而be able to可以用于各種時態。can（could）表示能力時，可用be able to代替。I can（=am able to）pay for the book.           我買得起那本書。He will be able to

8、tell you the news soon.         他很快就能告訴你消息了。She has been able to come to school.              她已經能去學校了。（2）maya.表示請求、許可May I borrow your pen？我可以借你的鋼筆用一用嗎？b.可能、或許Tomorrow I may go shopping.明天，我可能（或

9、許）去商店買東西。He might be our new teacher.他或許是我們的新老師。（3）musta.必須、應該（表示有做某一動作的必要或義務）You must buy a ticket.你必須買一張票。b.一定、準是（表示有把握的判斷或推測，一般只用于肯定句中）在You must這一句型中，它的意思與祈使句相同。You must get up early. =Get up early.你必須早起。You must study hard. =Study hard.你必須用功讀書。He must be our new teacher.他肯定是我們的新老師。2.表示推測的用法can ,

10、 could ,may ,might ,must 皆可用來表示推測，其用法如下：acould ,might 表示推測時不表示時態，其推測的程度不如can ,may。bcan ,could 用于否定句和疑問句中。句型：主語+ can't , couldn't +be +動詞ing（否定句）Can ,Could +主語 +be +動詞 ing（疑問句）They can't be cleaning the room now他們現在不可能在打掃房間。cmay ,might , must 用在肯定句中。句型：主語+ may ,might ,must +be +動詞 -ing （表

11、示對現在發生動作的推測）He must be sleeping . 他現在肯定在睡覺。d但如果上述這些詞 (must ,can't ) + have +過去分詞則指對過去已發生的事進行推測。The road is wet. It must have rained last night .地是濕的；昨天晚上肯定下雨了。There isn't any water on the road . It (can't ) couldn't have rained last night .地面上一個水滴都沒有，昨天不可能下雨了。（四） have to的用法1. have（ha

12、s）to +動詞原形have（has）to后面要用動詞原形。當主語為第三人稱單數時用has to，當句子是過去時用had to。We have to leave now.我們不得不現在就離開。He has to work on Sunday.他不得不在周日工作。I had to do my homework last Sunday.上周日，我不得不做作業。2. have to的否定句句型：主語+don't（doesn't, didnt, will not）have to+動詞原形You don't have to walk so fast.你不必走那么快。He will

13、 not have to buy a new coat next year.明年，他沒必要買新外衣了。3. have to的疑問句句型：Do（Does, Did, Will）+主語+have to +動詞原形？Do you have to study maths now？你現在必須學數字嗎？Yes，I do.是的，必須學。No，I don't（have to）。不，不必學。Did he have to ask the question？他非要問那個問題嗎？Yes，he did.是的。No，he didn't（have to）.不。4. must與have to比較must側重于

14、個人意志和主觀上的必要，have to側重于客觀上的必要。如果用于過去時態或將來時態時，則要用have to的相應時態來代替must。但must可用于間接引語中表示過去的必要或義務。My brother was very ill，so I had to call for the doctor in the middle of the night.我弟弟病得很厲害，我只得半夜里把醫生請來。（一般過去時）I haven't got any money with me，so I'll have to borrow some from my friend.我身上沒有錢，只好向朋友借點了

15、。（一般將來時）He said that they must work hard.他說他們必須努力工作。二、虛擬語氣虛擬語氣表示說話人的意愿、假設、猜測或建議。虛擬語氣不表示客觀存在的事實，謂語動詞用特殊的形式表示虛擬語氣。1 表示與現在事實相反時的謂語形式。從句主句過去式 (be和were)would (should、could)+ 動詞原形例如：If Tom were hungry, he would eat the bread. (In fact, Tom isnt hungry.)2 表示與過去事實相反的謂語形式。從句主句had + 過去分詞would (should、could) +

16、 have +過去分詞例如：If I had left a little earlier, I would have caught the early bus. (In fact, I didnt catch the bus.)3 表示與將來事實相反的謂語形式。從句主句動詞過去式should + 動詞原形were to + 動詞原形would (should、could) + 動詞原形例如：If they came tomorrow, we would told them about it. (In fact, they wont come tomorrow。)4 動詞wish后的賓語從句中，

17、謂語動詞可用過去式、過去完成式或would、might加原形。例如：I wish I were as strong as you.He wished I would stay with us.She wished I had attended the meeting yesterday.5 在有些動詞如：suggest、insist、order等動詞后，從句謂語動詞用“should + 動詞原形”，should可以省略。例如：He suggested that we (should) discuss the problem right now.6 在有些句型中如：It is important

18、 (necessary、natural、strange等) + that從句中的謂語動詞用should + 動詞原形，should可以省略。例如：It is necessary that the doctor (should) be sent there at once.7 在It is time that, I would rather that句式中從句謂語動詞用過去式。例如：It is time we went to bed.I would rather he came next week.第二節實戰演練一、復習時需注意的要點（一）情態動詞1、情態動詞在句中沒有人稱和數的變化。2、含有情

19、態動詞的句子改為否定句或疑問句不必加助動詞，只需要將情態動詞置于主語前，或在情態動詞后加上not。例如：Must I write a letter to cheer him up?You neednt wait for me.3、 情態動詞的過去式，例如cancould，maymight。但是少數情態動詞只有過去式，例如used to表示過去常常。must的過去式往往用had to代替。4、 情態動詞后還可接不定式的進行式、完成式和被動式。例如：He cant be doing his homework now. 他現在不可能在做功課。He must have attended the mee

20、ting last night. 昨晚他一定參加了會議。（二）虛擬語氣1、 在if條件句中，如果含有were , should或had等助動詞，if可以省去，句子用倒裝。例如：Were I you , I would buy this reference book.2、 should與would都可以用于if條件句的主句中，但should一般只用于第一人稱，would用于所有人稱。例如：If you were here , I would tell you the news .3、 某些條件可以用介詞短語without , but for 等來表示。例如：Without your help ,

21、 I could not have succeeded in passing the exam .4、 有時句子通過but或otherwise等詞來表示真實與虛擬的轉換，在這種情況下，只有不真實的部分用虛擬式。例如：I was ill yesterday；otherwise I would have played football with you . But for the heavy rain , we would have gone to the concert .5、 有suggest等詞的相應的名詞組成的同位語從句及表語從句用虛擬式。例如：I accepted my mothers

22、suggestion that I should eat an apple every day . 二、歷屆高考試題分析例1、There _ be any difficulty about passing the road test since you have practised a lot in the driving school. A. mustnt B. shant C. shouldnt D. neednt 答案：C【解析】根據經驗或慣例對某一情況進行推測，用should或ought to，常譯成“按理應該”或“可能會”。shouldnt是其否定形式。例2、Is John comi

23、ng by train?He should, but he _ not. He likes driving his car.A. must B. can C. need D. may答案為D。【解析】 come, go, leave, start等趨向動詞的進行時表示將來時，所以答語是對這一將來動作做出的推斷。may not“可能不；不一定”，根據he likes driving his car可以看出John可能乘火車來，也可能自己開車來。may not正好符合這一語境。must not“不準”；cannot“不可能”；need not“不必”。例3、It is hard for me to

24、 imagine what I would be doing today if I _ in love, at the age of seven, with the Melinda Cox Library in my hometown.A. wouldn't have fallen B. had not fallenC. should fall D. were to fall答案為B。【解析】根據句意和I would be doing可以判斷這是虛擬語氣。at the age of seven 是表示過去的時間狀語，if從句中的謂語要用had not fallen，表示對過去情況的假設

25、。由于主句中的謂語表示對現在的虛擬，條件句中的謂語表示對過去情況的虛擬，增加了試題的難題，但是，使用排除法可以容易地做出該題：should fall 和were to fall都可以用于條件句中表示對將來的虛擬；wouldn't have fallen不用于條件句中，所以都不能作為答案。譯文：如果我不在七歲時就迷戀上了我們家鄉的Melinda Cox圖書館，我真不能想象我今天會做什么。例4、You can't imagine that a well-behaved gentleman _be so rude to a lady.A. might B. need C. shoul

26、d D. would答案為C。【解析】 should用于表示感情，意向等句中的that從句，表示“竟然，居然”的驚訝，出乎意料。譯文：你難以想象一位行為體面的紳士會對一位女士那么粗魯。例5、What would have happened _, as far as up to the river bank?A. Bob had walked farther B. if Bob should walk fartherC. had Bob walked farther D. if Bob walked farther答案為C。【解析】因為主句的謂語動詞用了would have happened，所

27、以從句的謂語動詞要用過去完成時。在虛擬語氣中，如果條件狀語從句中的if省略，該句要倒裝。譯文：如果鮑勃走得遠一點，走到岸邊，會發生什么事呢? 例6、Mr. Bush is on time for everything. How _it be that he was late for the opening ceremony?A. can B. should C. may D. must答案為A。【解析】 can表示可能性的推測，常用于疑問句或否定句中；may表“可能性”常用于肯定句或否定句中；must常用于肯定句中表推測，“一定”的意思。注意：can not表示“不可能”，而may not表示

28、“或許不可能不”，兩者語氣上有區別。譯文：布什先生按時做好一切事。他來參加開幕式遲到了可能會是什么樣的情景呢? 例7、My sister met him at the Grand Theatre yesterday afternoon, so he _ your lecture.A. couldn't have attended B. needn't have attendedC. mustn't have attended D. shouldn't have attended答案為A。【解析】“情態動詞+不定式完成式”有各自的含義。must have done

29、表示對過去事情的肯定推測，多用于肯定句中；needn't have done表示過去本不必做的事情；shouldn't have done表示過去做了不該做的事情；can't (couldn't) have done表示對過去的否定性推測，意為“不可能”。所提供的情境My sister met him at the Grand 表示他不可能參加講座。例8、He hesitated for a moment before kicking the ball, otherwise he_ a goal.A. had scored B. scored C. would

30、score D. would have scored答案為D。【解析】根據otherwise可以判斷出要用虛擬語氣。表示過去發生的事要用would have scored。譯文：在踢球前他猶豫了一會兒，否則他就會射中球門。例9、Oh, I'm not feeling well in the stomach. I _ so much fried chicken just now.A. shouldn't eat B. mustn't have eaten C. shouldn't have eaten D. mustn't eaten答案為C。【解析】 j

31、ust now是表示過去的時間狀語。情態動詞在表示過去發生的事時，必須用“情態動詞+have+過去分詞的形式”。所以只能在選項B或C中確定答案。mustn't have eaten是一個錯誤選項，因為“mustn't+動詞”表示“禁止”，不表示判斷或推測。譯文：噢，我覺得胃不舒服。我剛才不應該吃那么多炸雞。例10、I was really anxious about you .You_ home without a word.A. mustn't leave B. shouldn't have leftC. couldn't have left D. n

32、eedn't leave答案為B。【解析】 should' t have done表示本來不應該做而做了，含責備意味。譯文：我真為你著急，你不應該不說一句話就離開了家。另外注意mustn't+動詞表示“禁止”。第三節鞏固練習Direction: Beneath each of the following sentences there are four choices marked A. B. C and D. Choose the best answer that completes the sentence.1. Isn' t that Ann's

33、husband over there?No, it _ be him . I'm sure he doesn't wear glasses.A. can't  B. must not C. won't   D. may not2.Youto the meeting this afternoon if you have something important to do.A. needn't to comeB. don't need comeC. don't need comingD. needn't

34、come 3. Heyou more help, even though he was very busy.A. might have givenB. might giveC. may have givenD. may give 4. I help you with some shoes, madam?Yes, I would like to try on those brown ones.A. Will B. Should C. May D. Must 5. The reason why they leave wasn't explained to us.A. had B. had

35、to C. must D. might 6. I searched for my wallet and it wasn't there. I thought Iit at home.A. leftB. have left C. might have leftD. could have left 7. I asleep because it took me a long time to realize that the telephone wasringing.A. could have fallen B. should have fallenC. must have fallen D.

36、 mustn't have fallen 8. The only thing that really matters to the children is how soon they return totheir school.A. can B. must C. have to D. ought to 9. I want to go to the chemist's, but you go with me.A. need not B. must not C. need D. cant10. I thought it over, butcome to no conclusion.

37、A. can B. could C. should D. would 11. What we get seems better than what we have.A. can B. could C. can't D. couldn't 12. My goodness! I've just missed the train. That's too bad. I am sure you it, if you had hurried. A. could have caught B. had caughtC. would catch D. could catch 13

38、. Look! What you've done! You more careful.A. may be B. had toC. should have been D. would be 14. I repeat the question?A. Shall B. Will C. Do you want that D. Do 15. Professor Li, many students want to see you. they wait here or outside!A. Do B. Will C. Shall D. Are 16. You read that book if yo

39、u don't want to.A. haven't B. can't C. mustn't D. needn't 17. Johnny, youplay with the knife; youhurt yourself.A. won't can't B. can'tshouldn'tC. shouldn'tmust D. mustn'tmay 18. It's nearly seven o'clock. Jackbe here at any moment.A. must B. need C

40、. can D. should 19. There were already 5 people in the car, but they managed to take me as well. It a comfortable journey.A. can't beB. shouldn't beC. couldn't have been D. mustn't have been 20. Tom ought not to me your secret, but he meant no harm.A. have told B. tellC. be telling C

41、. having told 21. Everyone is here. we start the meeting?A. Can B. Must C. Should D. Shall 22. I parked my car right here but now it's gone. It .A. must be stolenB. may be stolenC. must have stolen D. must have been stolen 23. He the work yesterday, but he didn't.A. must have finished B. nee

42、d have finishedC. finished D. should have finished 24. He did not pass the examination. As a good student, he.A. mustn't have failed B. may not have failedC. needn't have failed D. shouldn't have failed 25. it be true that Albert passed the test in geography?A. MayB. Should C. Could D. W

43、ould 26. You lead a horse to the water but you not make it drink.A. willcan B. maycanC. maydare D. darecan 27. Must we finish the composition in class? No, you .A. needn't B. mustn'tC. won't D. shouldn't 28. Her eyes were red. She .A. must cry B. must be criedC. must have been crying

44、 D. may cry 29. Mary his letter; otherwise she would have replied before now.A. has received B. must receiveC. couldn't have received D. shouldn't have received 30. I told Sally how to get here, but perhaps Ifor her.A. had to write it out B. must have written it outC. should have written it

45、out D. ought to write it out31. As usual, he put on a show as though his trip a great success. A. had been B. has been C. were D. was 32. Looking round the town, he felt as though he away for ages. A. has been B. was C. is D. had been 33. John is so strongly built that he looks as if he an elephant.

46、 A. lifts B. is lifting C. lifted D. could lift 34. He described the town as if he it himself. A. had seen B. has seen C. saw D. sees 35. At that thought he shook himself, as though he from an evil dream. A. woke B. wakes C. would wake D. had woke 36. Most insurance agents would rather you anything

47、about collecting claims until they investigate the situation. A. do B. dont C. didnt D. didnt do 37. Although most adopted persons want the right to know who their natural parents are, some who have found them wish that they the experience of meeting. A. hadnt B. didnt have had C. hadnt had D. hadnt

48、 have 38. He insisted that the sky _ clear up the following day. A. would B. should C. D. be 39. Without electronic computers, much of todays advanced technology . A. will not have been achieved B. have not been achieved C. would not have been achieved D. had not been achieved 40. He told her to return the book in time so that others a chance to read it . A. may