第九讲 情态动词与虚拟语气

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1、第九讲 情态动词与虚拟语气Modal verbs and subjunctive mood情态动词Modal verbs【考点概况】 一情态动词的语法特征1. 情态动词不能表示正在发生或已经发生的事情，只表示期待或估计某事的发生。2. 情态动词 除 ought 和 have 外，后面只能接不带 to 的不定式。3. 情态动词没有人称、数的变化，即情态动词第三人称单数不加-s。4. 情态动词没有非谓语形式，即没有不定式、分词等形式。 情态动词的分类和意义意义情态动词can, may, might, could, would, will, shall, must, should, ought to

2、, used to 二情态动词的基本用法1. can (could)1) 表示能力， could 主要指过去时间。例如： lean hear you perfectly well, donshout into my ears.别对我大声嚷嚷，我听得见你说话。 Could the girl speak before she went to school? 这女孩上学前能说话吗？2) 表示可能(理论上或是逻辑判断上)。例如： He cant (couldnt) finish the project on time. 他不可能准时完成工程。 No shouting or playing in wor

3、kspace, or you could interrupt other people. 工作区不许大声喧 哗，否则会影响其他人的工作。3) 表示允许。例如： Can I open the window? 我可以开窗吗？ He asked whether he could have a rest in the VIP-room. 他问他可不可以在贵宾室休息。4) 表惊异、怀疑、不相信等态度。主要用于否定句、疑问句或感叹句中。例如： Where can (could) they have gone to? 他们会去哪儿了呢？ How can you be so careless? 你怎么这么粗心

4、？5) 比较委婉客气地提出问题或陈述看法。例如： Can (Could) you help me? 帮我一把好吗？. Im afraid we couldnt give you an answer today. 恐怕我们今天不能给你答复。2may （might）1）表允许，might可以指过去时间，也可指现在时间，语气更委婉。例如： You may have whatever you like你喜欢什么就吃什么。 May （Might） I lend your book? 我可以借一下你的书吗？在回答以may引起的问句时，多避免用这个词,而用其它方式，如Yes, please. / Certa

5、inly./ Please don t / Youd better not. / No, you mustnt 等，以免显得太严峻或不客气。2）表可能（事实上）。可以指过去时间，也可以指现在时间，但语气更加不肯定。例如： He may be not at home. 他可能不在家。 She may know that news. 她可能知道这件事。3must1）表示义务。意为必须（主观意志）。例如： We must act, we must act quickly. 我们必须行动，立即行动 What must I do, mom? 我应该做什么呢，妈妈？一 You must go to bed

6、你必须上床睡觉。2）表示揣测。意为想必、准是、一定等，只用于肯定句。例如： So be it? For once, must be right! 就这样做？就一次，也许就是对的！ Shes wearing a diamond necklace. She must have a lot of money. 她戴着钻石项链，一定很 有钱。4shall1）表征询意见，用于第一、第三人称疑问句。例如： Shall I open it?我能打开它吗？ Shall we go to the theatre this evening? 我们今晚去看戏好吗?2）表说话人的意愿，有命令、允诺、警告、决心等意思，

7、用于第二、第三人称陈述句。 例如： Candidates shall remain in their seats until all the papers have been collected. 试卷全部收回 后考生才可离开座位。 （命令） If I finish the book, you shall get it. 我看完这本书你就可以看了。 （允诺） You shall be punished if you break the law. 违法就要受到法律的惩罚。 （警告） We shall never desert our true friends. 我们决不会抛弃真正的朋友。 （决心

8、）5will1）表意愿，用于各种人称陈述句。例如： He will help you if you turn for him. 如果你向他求助他会帮助你的。 I will do it. 我将做这件事。 If you will read the book, Ill lend it to you. 如果你愿意读这本书，我会把它借给你。2）表请求，用于疑问句。例如： Will you close the window? 请你把窗户关上好吗？ Wont you drink some more tea? 再来一点茶好吗？3）表示某种倾向或习惯性动作。例如： Human being will die wi

9、thout oxygen. 人没有氧气就不能活了。 The machine wont work. 这部机器坏了。6. should1）表义务。意为应该（某件事宜于做），用于各种人称。例如： You should be polite to your teachers. 你对老师应该有礼貌。 I often see lights in that empty house. Do you think I should report it to the police? 我经常看见那所空房子有光。你觉得我应不应该报警？2）表推测，意为想必、一定、照说应该、估计等。例如： The film should b

10、e very good as it is starring first-class actors. 这部新电影是一流演员主演 的，估计拍得很好。 They should be in New York by now. 照说他们现在应当已经到纽约了。3）（表示不确定）万一。例如： If you be interested, Il tell you the whole story.万一你有兴趣的话，我可以把整个故事讲给 你听。 If it should rain tomorrow, the sports meeting would be postponed. 万一明天下雨,比赛就延 期举行。7. w

11、ould1） 表意愿。例如：: They would not let him in because he was poorly dressed. 他们不让他进去因为他衣着破 旧。 I said I would do anything for you. 我说过我愿意为你做任何事。2) 表委婉地提出请求、建议或看法。例如： Would you mind cleaning the window? 请把窗户擦一下好吗？ They wouldnt have anything against it. 他们不会有什么反对意见。3) 表过去反复发生的动作或过去的一种倾向。例如：Every time she w

12、as in trouble, she would go to him for help. 她每遇到麻烦都会向他求助。、 8.ought to1) 表义务，意为应该(因责任、义务等该做)，口气比 should 稍重。例如： You are his father. You ought to take care of him你是他父亲，应当管他。 You oughtnt to smoke so much. 你不应该抽这么多烟。2) 表推测，暗含很大的可能，语气较弱。例如： Han Mei ought to know his telephone number. 韩梅该知道他的电话号码。 Theres

13、a fine sunset; it ought to be a fine day tomorrow. 今天有晚霞，明天应该是个好天。9. used to表示过去的习惯动作或状态，现在不复发生或存在。疑问式和否定式有两种。例如： There used to be a building at the street corner, but it has been pulled down.街道拐角处过去有座楼房，但现在拆了。 I usednt (didnt use) to smoke. 我过去不抽烟。 Used you (Did you use) to go to school on foot? 你过

14、去常步行去学校吗？10. 特殊情态动词need和dare的用法：need 和 dare 既可用作情态动词，也可用作实义动词。用作情态动词时，主要用于否定句和 疑问句。用作实义动词时，可用于各种句式。1) 用作情态动词。例如： You neednt telephone him now. 你现在不必打电话给他。 I dont think you need worry. 我想你不必发愁。 She dare not go out alone at night. 她晚上不敢一个人出去。 How dare you say Im unfair? 你竟敢说我不公平？2) 用作实义动词。例如： You dont

15、 need to do it yourself. 你不必亲自做这件事。 We need to tell them the news. 我们需要把这消息告诉他们。 The table needs painting (to be painted.). 桌子需要油漆一下。 We should dare to give our own opinion. 我们要敢于提出自己的观点。 He did not dare (to) look up. 他不敢抬头看。 I dare say hell come again. 我想他会再来的。【注意】(I dare say为固定习语)难点突破1. 情态动词后跟完成时和

16、进行时的用法1) 情态动词+动词完成时情态动词+动词完成时即情态动词+ have + done 分词，表示对过去行为或动作进行推测、 评论或判断。must have done 表示对过去某事的肯定猜测。其否定或疑问形式都用 can(could) 来表示。 例如： Since the road is wet, it must have rained last night. He cant have missed the way. I drew him a map. The dictionary has disappeared. Who could have taken it?当然对现在发生或将来

17、发生的事情，要用must do表示猜测，否定为cant do。例如： He must understand that we mean business. You must be hungry after a long walk.may / might have done表示推测过去某事也许发生了.may比might表示的可能性在说话 人看来稍大些。例如： I cant find my keys. I may / might have left them at the school yesterday.could have done 在肯定句型中， 往往用作委婉的批评. 本应该做什么，而没做;

18、有时也用作 猜测。例如： You could have told us earlier. Tom could have taken the dictionary.ought to / should have done 和 ought not to / shouldnt have done 用于对已发生的情况表示责 备、不满”，分别表示本应该和本不应该。例如： With all the work finished， I should have gone to the party last night. You ought not to have made fun of him. He is no

19、t the one you laugh at but learn from.neednt have done表示过去做了某事，但没有做的必要，意为本没必要。例如: (11) You neednt have waken me up; I dont have to go to work today.【注意】表示推测过去某动作发生的可能性时，就表示的可能性程度而言，must最大，could 其次，may更次之，might最小。例如：(12) I wonder how Tom knew about your past.He must / could / may / might have heard o

20、f it from Mary.2) 情态动词+动词进行时情态动词+行为动词进行时(即情态动词+ be + doing形式)，表示推测或评论某动作现在是 否正在进行。例如： He must be playing basketball in the room. She may be staying at home.3) 情态动词+动词完成进行时情态动词+行为动词完成进行时(即情态动词+ have been + v-ing 形式)，表示推测或评论过 去某动作是否正在进行或一直在进行。例如： They should have been passed the exam. He may / might h

21、ave been not in when you called him.三、几组词的辨异1. can 和 be able to1) 情态动词can只有两种形式，现在式can和过去式could，而be able to有多种时态形式 Mary can play the piano. She has been able to play it since she was five.玛丽会弹钢琴。她五岁起就会弹了。2) 用在过去时中，could经常表示能够做某事，事实上不一定去做，而was / were able to则 表示过去做成了某事。在否定句中两者可通用。He could play ping-p

22、ang ball but he dont feel like it now. 他会打乒乓球，但是他今天不想打。 Given more time, Ill be able to do it better. 如果给予更多的时间，我能做得更好。2. must 和 have tomust表示主观意志，而have to表示由于客观因素不得不做某事。must没有过去式，除 在间接引语中可用于表示过去时间，在直接引语中表示过去时间应该用had to代替。 She must finish her homework. 她必须完成家庭作业。We have to bait here and take some fo

23、od. 我们必须在这休息一会，吃点东西。3. would 和 used toWomen used to think they were on the shelf at 30.过去女人一到30 岁就认为是过了结婚年龄.(现在人们不这么认为。)He would play basketball at the afternoon when he lived in Hui Long guan. 在回龙观住的时候，他总是下午去打篮球。(可能现在仍有打篮球的习惯。)2) used to可表示过去的习惯动作和经常的情况，而would只表示过去的习惯动作。I used to get up early and t

24、ake an hours walk before breakfast. 我过去常常起床很早并且在早餐前散步一小时。【名师点拨】1. may1) 可否A. 用于问句。 May I use your phone?B. 用于陈述句。 You may come if you wish.2) 推断A. 现在可能。 He may know the answer.B. 过去可能。 He may have gone abroad.3) 用于状语从句，表示目的、让步等。Speak clearly so that they may understand you.Try as he may, he will not

25、 pass the exam.4) 祝愿。 May you be happy!2. might 轻微批评、抱怨。A. 针对现在： You might tell me if yoUre going to be late.B. 针对过去： You might at least have phoned me if youre not coming.3. must1) 必须、一定。A. 指现在或将来。You must give up smoking. I must remember to post the letter.B. 指过去用have的过去式had(比用must含义清楚)：I had to g

26、o to see the doctor.2) 否定式 must not/mustnt 表示“禁止、一定不”。Cars must not park in front of the entrance. We mustnt be late.3) 推断A. 现在可能。 He must know the answer.B. 过去可能。We must have read the same report.4) 责任、义务，与 should/ought to 含义类似。You must see the film; its wonderful.4. should /ought1) 责任、义务A. 指现在或将来。

27、The police should do something about it.The machine ought to be cleaned once a week.B. 指过去。You should have checked the time before you left.You ought to/should have told me about it earlier.2) ought to 还用于表示揣测。He ought to pass the exam.The water ought to have boiled now.We ought to be hearing from J

28、ane soon.5. shall1) 疑问形式征求意见，用于第一人称:What time shall I come?Lets do it again, shall we?Shall I open the window?You shall have the result of the exam tomorrow.2) 表示规定、许诺、命令、警告、决心等，用于各个人称I shall write to you at the end of the month.If you want a computer, you shall have one.A player shall be sent off f

29、or using bad language.6. need1) 表示“不必”，A. 用于否定句: You neednt come to the meeting.B. 用于含有半否定词的句子：C. 用于宾语从句时，主句为过去时，依然用 need:He says/said I neednt pay till the 30th.2) 用于疑问句: Need we come tomorrow?7. dare1) 表示“敢”，A. 用于否定句。I darent ask her to do that.B. 用于含有半否定词的句子：I hardly dare to think of it.2) 用于疑问句和

30、条件句：Dare you interrupt him? I wonder if she dared come home.3) 用于 I dare say, dont you dare 结构：I dare say youre right.Don t you dare touch that vase.8. have to 表示客观上的必要性，后接不定式.1) 肯定式： We have to be careful in such matters.2) 否定式和疑问式：You dont have to get up early.Do you have to leave so soon?3) 可用于各种

31、时态: Well have to help him as much as we can.4) 可用于各种语态: A lot of letters had to be answered.5) 可用于复合谓语: We may have to cancel the plan.9. had better/ best, d better1) 后接不定式的一般时或进行时(均不带 to)。A.接不定式的一般时：Wed better go before it gets dark.What had we better do?2) 接不定式的进行时： I think wed better be going.3)

32、had best 与 had better 相似： I had best be going now.【高考真题】1. Is John coming by train? He should, but he _ not. He likes driving his car.A. must B. canC. need D. mayKey: D解析：从上下文 coming by train 和 driving his car 可知有两种可能性，则关于 driving his car 的推测属于not sure 类，因此选D。2. It has been announced that candidates

33、 _ remain in their seats until all the papers have been collected.A. canB. willC. mayD. shallKey: D解析：根据上下文可知空格处应有一个表示意图、警告等含义的词语,shall就是这样一 个词语，它可用于各种人称。3. Oh， Im not feeling well in the stomach. I _ so much fried chicken just now.A. shouldnt eatB. mustnt have eatenC. shouldnt have eatenD. mustnt e

34、atKey: C解析：根据语境Im not feeling well”可知言者感到后悔，即动作应是发生在过去，因此 应选“情态动词+完成时的不定式”结构来表示对过去的推断。又，mustnt表示“禁止”， 所以不可选。4. Do you think our basketball players played very well yesterday?A. They were not nervous at allB. They were still youngC. They played naturallyD. They couldnt have done betterKey: D解析：问者询问“昨

35、天球打得如何”，应用对过去的情况的判断，故应选D。其余三选项所答非所问。又，not+比较级表示强调性的肯定。5. He _ here by now, for he took the early bus.A. ought to have arrivedB. must arriveC. may have arrivedD. can arriveKey: C解析：从took the early bus可知，arrive的动作应发生于过去，即句子应表示对过去情况 的推断，所以应该用含有完成时的不定式的选项。 ought to 表示“责任、义务”，不用于 表示对过去的推测，只有may have arri

36、ved合理。6. I wonder how he _ that to the teacher.A. dare to say B. dare sayC. not dare say D. dared sayKey: D解析：此从句中的动作应发生于过去，故dare应该用过去式dared。若发生于现在，则 应该用dare say（情态动词用法）或dares to say（行为动词用法，现在时）。又，dare的情 态动词用法否定式应为 dare not do sth.。7. I saw Ann in the library yesterday. You _ her; she is still abroa

37、d.A. must not seeB. cant have seenC. mustnt have seenD. couldnt seeKey: B解析：由“yesterday”可知应是对过去情况的推断，因此应该用“情态动词+完成时的不定 式”的结构来表示；又因“mustnt ”表示“禁止”而不可用。8. I _ them, but I wasnt able to.A. ought to have helpedB. must have helpedC. might helpD. neednt have helpedKey: A解析：应该用“情态动词+完成时的不定式”的结构来表示对过去情况的推断。

38、从“wasnt able to”可知言者原要“help them”，但限于能力而未实现；从表达“责任、义务”需要， 应该用 should/ought to 这样的情态动词。情态动词的用法：情态+原形 情态+完成Must have doneCan not have doneShall =order / promiseCan =sometimes9. Some people who dont like to talk much are not necessarily shy； they just be quietpeopleA. mustB. mayC. shouldD. WouldKey: B1

39、0. One of the few things yousay about English people with certainty （有把握）is thatthey talk a lot about the weather.A. needB. mustC. shouldD. canKey: D11. He did not regret saying what he did but felt that he it differently.A. could expressB. would expressC. could have expressedD. must have expressedK

40、ey: C12. Its the office! So you know eating is not allowed here.Oh, sorry.D. needA. must B. will C. mayKey: A虚拟语气Subjunctive mood考点概况】 一、语气的定义和种类1、语气：语气是动词的一种形式，它表示说话人对某一行为或事情的看法和态度。2、语气的种类：(1) 陈述语气: 表示动作或状态是现实的、确定的或符合事实的，用于陈述句、疑问句和 某些感叹句。例如： We are not here. What a de1icious cake it is!(2) 祈使语气: 表示

41、说话人的建议、请求、邀请、命令等。如: C1ose the door, p1ease。(3) 虚拟语气: 表示动作或状态不是客观存在的事实，而是说话人的主观愿望、假设或推 测等。例如: If I were you, I shou1d work hard.二、虚拟语气在条件从句中的用法 条件句有两类，一类是真实条件句，一类是虚拟条件句。如果假设的情况是有可能发生 的，就是真实条件句。在这种真实条件句中的谓语用陈述语气。例如: If it doesnrtain tomorrow, we wi11 c1imb up the hi11. 如果假设的情况是过去或现在都不存在的，或将来不大可能发生的，则是

42、虚拟条件句。例如: If I had seen her yesterday, I wou1d have to1d you about it. 在含有虚拟条件句的复合句中，主句和从句的谓语都要用虚拟语气。现将虚拟条件从句和主句的动词形式列表如下:从句主句与现在事实相反动词的过去式(be的过去式一般用 were)would/ should/ could/ might + 动词原形与过去事实相反had +过去分词would/ should/ could/ might + have+过去分词与将来事实相反动词过去式，should +动词原形，were to + 动词原形would/ should/ c

43、ould/ might + 动词原形注：主句中的should只用于I、we,但在美国英语中，should常被would代替；从句中的 should可用于各种人称。1、表示与现在事实相反的假设和结果。例如： If he were here I could explain to him.2、表示与过去事实相反的假设和结果。例如： If you had prepared in advance, you wouldnt be in such an awkward position.3、表示与将来事实可能相反的假设和结果。例如： If it were fine tomorrow, I would go

44、shopping.4、有时条件从句中的动作和主句中的动作发生的时间不一致(表示错综时间的虚拟语 气)，这时动词的形式要根据它所表示的时间加以调整。例如： If you had stuck around, you d have seen the fireworks.5、虚拟条件句可以转换成下列形式：(1) 省略连词if。在书面语中，如果虚拟条件从句中有were，had或should，可以把if省 略，把这几个词放到主语之前，构成主谓倒装。例如 ： Were I you I should wait.(2) 用介词短语代替条件状语从句。有时假设的情况并不用条件从句表示出来，而是通过 介词短语来表示。

45、例如 ： But for music (=Were it not for music), life would be dull.Without water (If there were not water), there would be no fish.在暗含虚拟条件的简单句中，虚拟语气可通过上下文表现出来。谓语动词用should/ would be 形式和 should/ would have been虚 拟形式。例如:What would I have done without you?(条件暗含在分词短语 without you 中)It would be easier to do i

46、t this way.(条件暗含在不定式短语to do it this way中)6、省去条件从句或主句：表示虚拟语气的主句或从句有时可以省略，但其含义仍可以推知。(1)省去条件从句。例如：You could have done your own homework (省去了If you had wanted to)(事实是:你自己没写家庭作业，因为你不想写。 )(2)省去主句(常用以表示愿望)。例如: If my grandmother were with me! (事实是:祖母已不在世。)三、虚拟语气的其他用法1、虚拟语气在主语从句中的用法：在It is important (strange

47、, natural, necessary)that 这类句型里，that所引导的主语从句中的谓语动词常用“should十动词原形”结构，表示某事 是重要、 奇怪、 自然、 必要等意义。如: It is necessary that every student (should) work hard.2、虚拟语气在宾语从句中的用法：(1)在动词wish后的宾语从句中，表示与现在或过去的事实相反，或对将来的主观愿望， 从句通常省略连词 that。1) 表示对现在情况的虚拟，从句动词用过去式或过去进行式(be动词一般用were)。 例如: I wish I could argue with you.2

48、) 表示对过去情况的虚拟，从句动词常用had十过去分词。例如:I wish I hadnt become so conscious of every little nuance.3) 表示对将来的主观愿望，谓语动词形式为-would十动词原形”。此时要注意，主句的主 语与从句的主语不能相同，因为主句的主语所期望从句动作能否实现，取决于从句主语的态 度或意愿(非动物名词除外)。例如: I wish it would stop raining.(2) 在 suggest， demand， order， propose， insist， command， request， desire 等动词后的

49、宾语从句中，谓语动词用“should +动词原形”，表示建议、要求、命令等。例如:I request that he should leave.3、虚拟语气在状语从句中的用法(1) 在带有even if/ even though引导的让步状语从句的主从复合句中，主句和从句都用虚 拟语气，动词形式与含有非真实条件句的虚拟语气相同。例如: Even if he had been ill, he would have worked hard.(2) 由as if或as though引导的状语从句表示比较或方式时。从句谓语形式为动词的过去 式(be 用 were)或 “had 十过去分词。例如：Don

50、t treat me as if I were a child.注:如果表示的事情可能会发生，那么方式状语从句中的谓语动词可用陈述语气。(3) 在in order that或so that引导的目的状语从句中，谓语动词多用“could或might (有 时也用 should) + 动词原形”。例如: I study hard, so that I may not fail in the examinations.虚拟语气表示将来，动词形式一般用过去式，意思是该干某事的时候了。例如: Its (high) time we did housework.5、虚拟语气在简单句中的用法(1) 情态动词的

51、过去式用于现在时态时，表示说话人的谦虚、客气、有礼貌，或委婉的语 气，常见于日常会话中。例如 It would be better if the school authorities should see to it.(2) 在一些习惯表达中。如: I would rather not tell you.(3) 用“may +动词原形”表示祝愿、但愿”，此时may须置于句首(多用于正式文体 中)。例如： May you have a fine trip! 旅途愉快！May you live happily! 生活快乐！【名师点拨】1)suggest /insist / order/ deman

52、d /request / require advise prefer that sb. should do sth.would rather thatIt is high time thatIt is my suggestion thatI wish thatHow I wish thatI would / could / might do if it were/didI should do it didI would do it were to do 将来I would do it didI would do it should doI would have done if it had d

53、oneIf I had studied last night, I would not be so worried about the exam.I went to the match last night. How I wish I had stayed at home.例句：How I wish I had a neck like that of a giraffe!Wish you a happy birthday!If I had a pair of wings, I would fly to school every day!2)建议、要求、命令：(should) do(1) I i

54、nsist that he stay here.(2) I suggested that you give me a hand.(3) His face suggests that he is very happy. (真实：表明)(4) She insisted that she had done nothing wrong. (真实：坚持认为)3) I wish that./ If only .(1) I wish I were you.(2) I wish you had come yesterday.(3) If only he could help me.比较：I wish that

55、 you could come and join us but you are not here.I hope that you can come and join us and Im sure you will have a nice time.【高考真题】1. You didnt let me drive. If we in turn, you so tired.A. drove; didnt getB. drove; wouldnt getC. were driving; wouldnt getD. had driven; wouldnt have gotKey: D2. When a

56、pencil is partly in a glass of water, it looks as if it .A. breaksB. has brokenC. were brokenD. had been brokenKey: C3. It is hard for me to imagine what I would be doing today if I in love, at the age ofseven, with the Melinda Cox Library in my hometown.A. wouldnt have fallenB. had not fallenC. should fallD. were to fallKey: B