情態(tài)動(dòng)詞和虛擬語氣講義.doc

第五章 情態(tài)動(dòng)詞和虛擬語氣一、情態(tài)動(dòng)詞的語法特征(1)情態(tài)動(dòng)詞不能表示正在發(fā)生或已經(jīng)發(fā)生的事情，只表示期待或估計(jì)某事的發(fā)生。(2)情態(tài)動(dòng)詞 除ought 和have 外，后面只能接不帶to 的不定式。(3)情態(tài)動(dòng)詞沒有人稱，數(shù)的變化，即情態(tài)動(dòng)詞第三人稱單數(shù)不加-s。(4)情態(tài)動(dòng)詞沒有非謂語形式，即沒有不定式、分詞、動(dòng)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(gè)條件，多半不是事實(shí)，或與事實(shí)相反。 高考重點(diǎn)要求：1、情態(tài)動(dòng)詞的基本用法2、情態(tài)動(dòng)詞表示推測(cè)的語義差別3、情態(tài)動(dòng)詞后接不定式完成體的不同意義4、虛擬語氣中情態(tài)動(dòng)詞的用法第一節(jié) 知識(shí)點(diǎn)概述一、情態(tài)動(dòng)詞 （一）情態(tài)動(dòng)詞種類1. can表示體力或腦力方面的“能力”、“技能”或根據(jù)客觀條件能做某種動(dòng)作的“可能性”, 但表示人的體力或智力的具體動(dòng)作時(shí)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(xiàng)工作。2. may表示“允許，可以”，相當(dāng)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(yuǎn)點(diǎn)為好。You might as well go home now.你還是現(xiàn)在回家為好。3. must表示“必須”或“應(yīng)當(dāng)”、“一定”。4. have to 加動(dòng)詞原形，表示“不得不”，“必須”，它比must更強(qiáng)調(diào)客觀。Tom had to work into the deep night every day to earn a living. 湯姆為了生計(jì)每天都得工作到深夜。5. should 表示“勸告”，“建議”或“義務(wù)”時(shí)，譯作“應(yīng)當(dāng)”，或表示“預(yù)測(cè)”和“可能”。He should take care of his parents as they are old enough not to live on themselves. 由于父母親老了，不能自理，他應(yīng)當(dāng)照顧他們。He should be there now. 他應(yīng)該在那兒。should have done在虛擬語氣中表示“責(zé)備或后悔”。6. ought ，只有一種形式，且ought后必須加to，然后跟接動(dòng)詞原形表示“有義務(wù)”或“必要”做某事，譯為“應(yīng)當(dāng)，應(yīng)該”。7. dare 可以用作情態(tài)動(dòng)詞，后面跟不帶to的動(dòng)詞不定式，這主要用于否定句中，它本身可有現(xiàn)在時(shí)第三人稱單數(shù)，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(tài)動(dòng)詞在一般時(shí)否定句中的用法cant(cannot) 表示“不可能”， may not 表示“不可以”， mustnt(must not) 表示“一定不要”，“不許可”，neednt (need not) 表示“不必”，dare not 動(dòng)詞原形表示“不敢”。He cant finish his essay by this time. 現(xiàn)在他不可能寫完論文。He may not sleep now. 他或許現(xiàn)在沒在睡覺。You mustnt criticize her in that way. 你不應(yīng)那樣批評(píng)她。You neednt come tomorrow. 你明天沒必要來了。He dared not meet his fiance. 他不敢見女朋友。（三）can，may，must三者用法比較can，may，must是三個(gè)最重要的情態(tài)動(dòng)詞，其基本句型如下：肯定句：主語+can，may，must +動(dòng)詞原形否定句：主語+can，may，must +not +動(dòng)詞原形疑問句：Can，May，Must +主語+動(dòng)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(huì)She can run fast，but I cant.她很會(huì)跑，但是我不會(huì)。b.表示可能；能夠I can 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(xiàn)在式和過去式，而be able to可以用于各種時(shí)態(tài)。can（could）表示能力時(shí)，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 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(jīng)能去學(xué)校了。（2）maya.表示請(qǐng)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(yīng)該（表示有做某一動(dòng)作的必要或義務(wù)）You must buy a ticket.你必須買一張票。b.一定、準(zhǔn)是（表示有把握的判斷或推測(cè)，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(cè)的用法can , could ,may ,might ,must 皆可用來表示推測(cè)，其用法如下：acould ,might 表示推測(cè)時(shí)不表示時(shí)態(tài)，其推測(cè)的程度不如can ,may。bcan ,could 用于否定句和疑問句中。句型：主語+ cant , couldnt +be +動(dòng)詞ing（否定句）Can ,Could +主語 +be +動(dòng)詞 ing（疑問句）They cant be cleaning the room now他們現(xiàn)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(dòng)詞 -ing （表示對(duì)現(xiàn)在發(fā)生動(dòng)作的推測(cè)）He must be sleeping . 他現(xiàn)在肯定在睡覺。d但如果上述這些詞 (must ,cant ) + have +過去分詞則指對(duì)過去已發(fā)生的事進(jìn)行推測(cè)。The road is wet. It must have rained last night .地是濕的；昨天晚上肯定下雨了。There isnt any water on the road . It (cant ) couldnt have rained last night .地面上一個(gè)水滴都沒有，昨天不可能下雨了。（四） have to的用法1. have（has）to +動(dòng)詞原形have（has）to后面要用動(dòng)詞原形。當(dāng)主語為第三人稱單數(shù)時(shí)用has to，當(dāng)句子是過去時(shí)用had to。We have to leave now.我們不得不現(xiàn)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(yè)。2. have to的否定句句型：主語+dont（doesnt, didnt, will not）have to+動(dòng)詞原形You dont have to walk so fast.你不必走那么快。He will 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(dòng)詞原形？Do you have to study maths now？你現(xiàn)在必須學(xué)數(shù)字嗎？Yes，I do.是的，必須學(xué)。No，I dont（have to）。不，不必學(xué)。Did he have to ask the question？他非要問那個(gè)問題嗎？Yes，he did.是的。No，he didnt（have to）.不。4. must與have to比較must側(cè)重于個(gè)人意志和主觀上的必要，have to側(cè)重于客觀上的必要。如果用于過去時(shí)態(tài)或?qū)頃r(shí)態(tài)時(shí)，則要用have to的相應(yīng)時(shí)態(tài)來代替must。但must可用于間接引語中表示過去的必要或義務(wù)。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(yī)生請(qǐng)來。（一般過去時(shí)）I havent got any money with me，so Ill have to borrow some from my friend.我身上沒有錢，只好向朋友借點(diǎn)了。（一般將來時(shí)）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(shè)、猜測(cè)或建議。虛擬語氣不表示客觀存在的事實(shí)，謂語動(dòng)詞用特殊的形式表示虛擬語氣。1 表示與現(xiàn)在事實(shí)相反時(shí)的謂語形式。從句主句過去式 (be和were)would (should、could)+ 動(dòng)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(shí)相反的謂語形式。從句主句had + 過去分詞would (should、could) + 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(shí)相反的謂語形式。 從句主句動(dòng)詞過去式should + 動(dòng)詞原形were to + 動(dòng)詞原形would (should、could) + 動(dòng)詞原形例如：If they came tomorrow, we would told them about it. (In fact, they wont come tomorrow。)4 動(dòng)詞wish后的賓語從句中，謂語動(dòng)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(dòng)詞如：suggest、insist、order等動(dòng)詞后，從句謂語動(dòng)詞用“should + 動(dòng)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 (necessary、natural、strange等) + that從句中的謂語動(dòng)詞用should + 動(dòng)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(dòng)詞用過去式。例如：It is time we went to bed.I would rather he came next week.第二節(jié) 實(shí)戰(zhàn)演練一、復(fù)習(xí)時(shí)需注意的要點(diǎn)（一）情態(tài)動(dòng)詞1、情態(tài)動(dòng)詞在句中沒有人稱和數(shù)的變化。2、含有情態(tài)動(dòng)詞的句子改為否定句或疑問句不必加助動(dòng)詞，只需要將情態(tài)動(dòng)詞置于主語前，或在情態(tài)動(dòng)詞后加上not。例如：Must I write a letter to cheer him up?You neednt wait for me.3、 情態(tài)動(dòng)詞的過去式，例如cancould，maymight。但是少數(shù)情態(tài)動(dòng)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(tài)動(dòng)詞后還可接不定式的進(jìn)行式、完成式和被動(dòng)式。例如：He cant be doing his homework now. 他現(xiàn)在不可能在做功課。He must have attended the meeting last night. 昨晚他一定參加了會(huì)議。（二）虛擬語氣1、 在if條件句中，如果含有were , should或had等助動(dòng)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 , I could not have succeeded in passing the exam .4、 有時(shí)句子通過but或otherwise等詞來表示真實(shí)與虛擬的轉(zhuǎn)換，在這種情況下，只有不真實(shí)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(yīng)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 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(jù)經(jīng)驗(yàn)或慣例對(duì)某一情況進(jìn)行推測(cè)，用should或ought to，常譯成“按理應(yīng)該”或“可能會(huì)”。shouldnt是其否定形式。例2、Is John coming by train?He should, but he _ not. He likes driving his car.A. must B. can C. need D. may答案為D?！窘馕觥?come, go, leave, start等趨向動(dòng)詞的進(jìn)行時(shí)表示將來時(shí)，所以答語是對(duì)這一將來動(dòng)作做出的推斷。may not“可能不；不一定”，根據(jù)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(zhǔn)”；cannot“不可能”；need not“不必”。 例3、It is hard for me to 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. wouldnt have fallen B. had not fallenC. should fall D. were to fall答案為B。【解析】 根據(jù)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(shí)間狀語，if從句中的謂語要用had not fallen，表示對(duì)過去情況的假設(shè)。由于主句中的謂語表示對(duì)現(xiàn)在的虛擬，條件句中的謂語表示對(duì)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(duì)將來的虛擬；wouldnt 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(shí)就迷戀上了我們家鄉(xiāng)的Melinda Cox圖書館，我真不能想象我今天會(huì)做什么。 例4、You cant imagine that a well-behaved gentleman _be so rude to a lady.A. might B. need C. should D. would答案為C?！窘馕觥?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(huì)對(duì)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?！窘馕觥?因?yàn)橹骶涞闹^語動(dòng)詞用了would have happened，所以從句的謂語動(dòng)詞要用過去完成時(shí)。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(yuǎn)一點(diǎn)，走到岸邊，會(huì)發(fā)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(cè)，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(cè)，“一定”的意思。注意：can not表示“不可能”，而may not表示“或許不可能不”，兩者語氣上有區(qū)別。譯文：布什先生按時(shí)做好一切事。他來參加開幕式遲到了可能會(huì)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. couldnt have attended B. neednt have attendedC. mustnt have attended D. shouldnt have attended答案為A?！窘馕觥?“情態(tài)動(dòng)詞+不定式完成式”有各自的含義。must have done表示對(duì)過去事情的肯定推測(cè)，多用于肯定句中；neednt have done表示過去本不必做的事情；shouldnt have done表示過去做了不該做的事情；cant (couldnt) have done表示對(duì)過去的否定性推測(cè)，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 score D. would have scored答案為D?！窘馕觥?根據(jù)otherwise可以判斷出要用虛擬語氣。表示過去發(fā)生的事要用would have scored。譯文：在踢球前他猶豫了一會(huì)兒，否則他就會(huì)射中球門。例9、Oh, Im not feeling well in the stomach. I _ so much fried chicken just now.A. shouldnt eat B. mustnt have eaten C. shouldnt have eaten D. mustnt eaten答案為C。【解析】 just now是表示過去的時(shí)間狀語。情態(tài)動(dòng)詞在表示過去發(fā)生的事時(shí)，必須用“情態(tài)動(dòng)詞+have+過去分詞的形式”。所以只能在選項(xiàng)B或C中確定答案。mustnt have eaten是一個(gè)錯(cuò)誤選項(xiàng)，因?yàn)椤癿ustnt+動(dòng)詞”表示“禁止”，不表示判斷或推測(cè)。譯文：噢，我覺得胃不舒服。我剛才不應(yīng)該吃那么多炸雞。 例10、I was really anxious about you .You_ home without a word.A. mustnt leave B. shouldnt have leftC. couldnt have left D. neednt leave答案為B?！窘馕觥?should t have done表示本來不應(yīng)該做而做了，含責(zé)備意味。譯文：我真為你著急，你不應(yīng)該不說一句話就離開了家。另外注意mustnt+動(dòng)詞表示“禁止”。 第三節(jié) 鞏固練習(xí)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 Anns husband over there?No, it _ be him . Im sure he doesnt wear glasses.A. cant B. must not C. wont D. may not2.You to the meeting this afternoon if you have something important to do.A. neednt to come B. dont need comeC. dont need comingD. neednt come 3. He you more help, even though he was very busy. A. might have given B. might giveC. may have given D. 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 wasnt explained to us. A. had B. had to C. must D. might 6. I searched for my wallet and it wasnt there. I thought I it at home.A. left B. have left C. might have left D. 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. mustnt 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 chemists, but you go with me. A. need not B. must not C. need D. cant10. I thought it over, but come to no conclusion. A. can B. could C. should D. would 11. What we get seems better than what we have. A. can B. could C. cant D. couldnt 12. My goodness! Ive just missed the train. Thats too bad. I am sure you it, if you had hurried. A. could have caught B. had caughtC. would catch D. could catch 13. Look! What youve 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 you dont want to. A. havent B. cant C. mustnt D. neednt 17. Johnny, you play with the knife; you hurt yourself.A. wont cant B. cantshouldntC. shouldntmust D. mustntmay 18. Its nearly seven oclock. Jack be here at any moment. A. must B. need C. 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. cant beB. shouldnt beC. couldnt have been D. mustnt have been 20. Tom ought not to me your secret, but he meant no harm.A. have told B. tellC. be telling C. 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 its gone. It .A. must be stolen B. may be stolenC. must have stolen D. must have been stolen 23. He the work yesterday, but he didnt.A. must have finished B. need have finishedC. finished D. should have finished 24. He did not pass the examination. As a good student, he . A. mustnt have failed B. may not have failedC. neednt have failed D. shouldnt have failed 25. it be true that Albert passed the test in geography? A. MayB. Should C. Could D. Would 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. neednt B. mustntC. wont D. shouldnt 28. Her eyes were red. She . A. must cry B. must be criedC. must have been crying D. may cry 29. Mary his letter; otherwise she would have replied before now. A. has received B. must receiveC. couldnt have received D. shouldnt have received 30. I told Sally how to get here, but perhaps I for her.A. had to write it out B. must have written it outC. should have written it 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. 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 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 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 have B. will have C. would have D. might have 41. It is time that the government measures