高中英语情态动词和虚拟语气讲义.doc

情态动词和虚拟语气
1 情态动词的用法
一、情态动词的语法特征。
情态动词和助动词一样，都是辅助性的动词，用来帮助构成不同的时态和语态，表示说话者的某种情态，没有人称和数的变化。情态动词主要有can, may, must, could, might, shall , should, will, would, ought to, need, dare等。
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,即动词原形。
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。
二、情态动词的基本用法。
1、can, could
（1）表示能力，意为“能，会”：The smallest good habits can make a big difference.[福建2014]
It was several minutes before I could take in what he was saying.[湖北2014}
（2）表推测，意为“可能”，用于否定句或疑问句中，can比could语气强：This can’t/couldn’t be done by him.
（3表示请求或允许，在疑问句中可以用could代替can，语气更委婉。
Could I use your phone,please?
（4）表示理论上的可能性。Always believe that good things are possible,and remember that mistakes can be lessons that lead to discoveries.
（5）用于否定句或疑问句，表示惊异、怀疑、不相信等态度。
He can’t do this. / Can this be done by him?
（6）用于固定习语中：can’t...too/enough表示“无论...也不为过”；can’t help doing sth表示“禁不住做某事”：You can’t be too careful while driving. / Hearing the story,I couldn’t help laughing.
【易混易错】can和be able to的区别：
（1）都可以表示能力，有时可以互换。
（2）be able to可以表示“终于做成某事”有更多时态和人称的变化，还可以与某些情态动词或系动词连用，如might，ought to，seem等，be able to还可以用非谓语动词形式。
He seemed to be able to put complicated thoughts in simple words.
She grasped my hand,not being able to say anything.
2、may,might
（1）表示请求和许可，疑问句中可互换，might语气更委婉。Might I borrow your computer?
（2）表示可能性，可以对现在、将来或过去进行推测，通常用于肯定句和否定句，might比may语气弱。
Parents may scold their children when they are untidy but they should also understand that their room is their own private space.[广东2014]
（3）表示祝愿，常用结构为“May+主语+Vo”.
（4）用于固定习语中“may/might as well + Vo”意为“不放，倒不如，最好”；“may/might well do+Vo”意为“最好做”。
【易错警示】 may作“可以”讲时，其否定回答用mustn’t，表示“不可以，禁止”。
--May I use your car? --No,you mustn’t.
3、must
（1）表示义务，意为“必须”（主观意志）回答must的一般疑问句时，若是否定回答，不用mustn’t，而用needn’t/don’t have to，表示“不必”的意思。
【易混辨析】must和have to的区别：
1）must表示出于主观意识必须要做某事，have to表示由于某种客观原因而不得不做某事，除此之外，have to自身有人称和时态的变化：It was then that I started to appreciate the tough choices she had to make on comparing her family and work.[天津2014]
2）have to 表示义务或习惯动作，must表示重要或急迫的事情。
She has to be at the office before eight every day.
You must go to the manager at once, or you’ll be dismissed.
（2）表示猜测，推测，意为“一定”。常用于肯定句；对现在或未来的事情推测用must do，对正在进行的事情推测用must be doing，对过去发生的事情推测用must have done结构。
He thought Joe must be dead,but he didn’t want to leave immediately.[课标全国2014]
Hurry up! They must be waiting for us now.
（3）用于否定句表示禁止。Smoking must not be allowed in the office.
（4）表示“偏要，非要...不可”。Must you make so loud noise?
4、shall
（1）用于第一、第三人称疑问句，表示征求对方的意见或请示。
Shall I tell Brett to come over straight after school tomorrow?[江西2014]
（2）用于第二、三人称的陈述句，表示说话人给对方的命令、警告、允诺和威胁。
I promise he shall get a present for his birthday.
（3）用于条约、法令、法律、规定等，意为“必须”。
It has been announced that candidates shall remain in their seats until all the papers have been collected.
5、should,ought to
（1）表示责任、义务、劝告、建议等，意为“应该”，表示责任或义务时，ought to=should，只是前者语气更重。
Why shouldn’t we buy the lady a flower?I will make her feel better.[陕西2014]
You ought not to be so selfish.
（2）should表示出乎意料的语气，意为“竟然，居然”。
That he should speak to you like that is quite astonishing.
→用在I’m surprised, it worries me, it’s a pity, it’s unthinkable等结构后面的句子中表示惊讶、忧虑、惋惜、欢欣等情绪。
I’m surprised that he should eat so little every day.
It’s a pity that she should fail in the entrance examination.
（3）should表示根据经验或常理的推断：The watch should be OK tomorrow.
（4）should和ought to表示推测，指预期的可能性，意为“应该，估计”
He ought to/should be here on time—he started early enough.
6、will,would
（1）用于表示意志或意愿。will指现在，would指过去。
I will never do that again. / They said that they would help us.
（2）表示“请求；建议”。用would比will委婉、客气些，句末用won’t you表达邀请的语气
Will you please take a message for him? / Would you please pass him the book？
（3）表示习惯性动作，“总是”“惯于”，will指现 在，would指过去：Fish will die without water.
（4）表示预料或猜想：It would be about ten when he left home.
（5）表示命令、强迫：All will arrive before 7:45
（6）表示意愿或者固执地坚持：She won’t lend me the money. / The window won’t open
（7）will表示规律性的“注定会”。
Wearing proper clothes is important too,form locals will judge you by what you wear.[重庆2014]
7、need/dare：need/dare可以做助动词，也可以做行为动词
Father sent me the book, so I didn’t need to write to him for it.
Father sent me the book, so I needn’t have written to him for it.
Most people hat Harry but they didn’t dare to say so.
【注意】作情态动词用，need/dare只用于疑问句和否定句，作实义动词可用于各种时态。

【思维拓展】must needs 和needs must
needs为副词,相当于necessarily, of necessity;二者均可表示必须，必定，不得不，但must needs 还可以表示偏偏，偏要：I must needs go there now. / Needs must when the devil drives.
〖考法1——考查情态动词的基本用法〗
1、 [天津2016] It was really annoying,I_____________get access to the data bank you had recommended.
2、 [北京2015] --Can’t you stay a little longer?--It’s getting late.I really ____________go now.My daughter is home alone.
3、 [安徽黄山2015质检] --I’m afraid I have to leave now,for you see,he is waiting for me.--Well,if you ___________,at least wait till the heavy rain stops.
4、 [安徽江淮2015联考] As the deadline is drawing near,no one _____________have leave with his own work uncompleted.
5、 [重庆2014] I’ve ordered some pizza,so we ______________ worry about cooking when we get home tired.
6、 [四川2014] I still remember my happy childhood when my mother ____________take me to Disneyland on weekends.
7、 [重庆2012] --____________you interrupt now?Can’t you see I’m on the phone?--Sorry,but it’s urgent.
8、 [成都2015二诊]Film reviewers are surprised to find that Han Han’s first film,The Continent,___________be such a huge success.
9、 [江苏无锡2015期末质检] As is required,all the participants ____________remain standing with one leg until the whistle is blown.
10、 [江苏2014] It was sad to me that they,so poor themselves,_________bring me food.
11、 [课标全国2013] The door _____________open,no matter how hard she pushed.
12、 [课标全国2012] I _______________use a clock to wake me up because at six each morning the train comes by my house.
13、 Liza ________________well not want to go on the trip—she hates traveling.
14、 --Have you heard of the news that Britain’s former Prime Minister,Baroness Thatcher,died on April 18th ?--Yes.____________________she rest in peace.
15、 With the help of the firemen,they _____________________ leave the burning house.(could/were able to)
16、 ________________that day come soon!
17、 Since it’s a fine day,we ________________ as well walk.
18、 You ______________use my computer as long as you promised to return on time.
19、 The interviewees are waiting outside the office.______________they come in right now?
20、 It’s 4:30.They __________________be in New York by now.
三、情态动词+have done的用法。
1、表示推测的情态动词的层次比较
情态动词的“推测”功能。如：can, could, may, might, must皆可表示推测，使用时要注意以下几点：
（1）注意语气。语气较强用must, cannot, couldn’t; 语气较弱用may, might或can, could。
（2）注意句式。在肯定句中，一般用may, might, must; 在否定句、疑问句中常用can, could。
（3）注意时态。表示对现在或将来的情况的推测，此时通常用“情态动词＋动词原形”结构； 表示对现在或将来正在进行的情况进行推测，通常用“情态动词＋进行体”结构； 表示对过去情况的推测，通常用“情态动词＋完成体”结构。
2、情态动词+ have done
（1）must have done表示对过去情况的肯定推测。意为“一定做了某事”，否定为can’t have done，意为“不可能做了某事”，没有mustn’t have done的形式。
（2）may / might have done表示过去可能发生过某事，也可以表示对过去的虚拟，表示“本可以做却没做”
（3）could have done表示过去可能发生，但并未发生，含有埋怨或训斥之意；也可表示对过去可能发生的事情的一种推测。
（4）should / ought to have done表示过去本该做（某事）而事实上未做；should not / ought not to have done表示过去本不该做（某事）但事实上却做了，含有批评、责备之意。
（5）need have done表示过去本来有必要去做（某事），但事实上没有做；need not have done表示过去本没有必要做（某事），但事实上做了。
（6）would rather/sooner have done表示“当时宁愿做了某事”，其否定式would rather not have done表示相反的含义，两者都表示“后悔”之意。
（7）had better have done用于事后的建议，含轻微责备的口吻，意为“当时最好做了某事”，其否定式had better not have done表示相反的含义。
〖考法2——考查情态动词+have done的用法〗
1、 [安徽2014] People are recycling many things which they ______________________(throw) away in the past.
2、 [陕西2015] My book,The House of Hades,is missing.Who ___________have taken it?
3、 [浙江2013] I ______________________enjoy) myself more—it was a perfect day.
4、 [安徽2013] I _______________________(go) to my cousin’s birthday party last night,but I was not available.
5、 Tom ought not to ________________(tell) me your secret,but he meant no harm.
6、 --The fire in the supermarket last night was terrible!--They ________________have taken some measures to prevent it occurring.
四、情态动词的反义疑问句
1．当陈述句部分有情态动词must时
（1）must表示“必须、禁止“时，反意疑问部分要用must (mustn’t)
You mustn’t stop your car here, must you?
（2）must表示“有必要”时，反意疑问句部分要用needn’t
You must see the doctor, needn’t you?
（3）当must用来表示对现在的情况进行“推测”时，反意疑问部分要根据must后面的动词采用相应的形式：He must be good at maths, isn’t he?
（4）当must用来表示对过去的情况进行“推测”（must + have done）时：
a). 单纯表示对过去的推测, 与现在无关, 反意疑问句附加部分用过去式。
b). 表示对过去的推测且影响到现在或持续现在, 反意疑问句附加部分用现在完成式。
She must have read the novel last week, didn’t she?
He must have lived here at least ten years, hasn’t he?
（5）当陈述部分含有情态动词used to时，疑问部分可用usedn’t或didn’t　　
The old man used to smoke, didn’t he?或usedn’t he?
（6）当陈述部分带有情态动词ought to时，疑问部分用oughtn’t或shouldn’t
We ought to read this book, oughtn’t we?或shouldn’t we?
（7）当陈述部分含有had better时，疑问部分用had 　
You’d better finish your homework now, hadn’t you?
（8）陈述部分有have to +v. (had to + v.)，疑问部分常用don't +主语（didn't +主语）
We have to get there at eight tomorrow, don't we?
（9）陈述部分有would rather +v.，疑问部分多用 wouldn't +主语
He would rather read it ten times than recite it, wouldn't he?
（10）带情态动词dare或need的反意疑问句，疑问部分常用 need (dare ) +主语
We need not do it again, need we ? / He dare not say so, dare you/he?
2 虚拟语气的用法
——此部分讲义编于2015.5.18
一、虚拟语气的概念：
虚拟语气表示说话人的愿望、假设、建议或者猜测而不表示客观存在的现实。英语中的语气分三类：陈述语气、祈使语气、虚拟语气。如果我们说的不是事实，也不是要求、命令、劝告等，而只是一种假设、愿望、建议或是一种实现不了的愿望，就用虚拟语气。虚拟语气常用在条件句及其他一些从句中。
二、条件句：
条件句分两种，真实条件句和虚拟条件句。只有在虚拟（非真实）条件句中，才会用虚拟语气，而在真实条件句中，要用陈述语气。请比较：
（1）If it is sunny tomorrow,we will go to the zoo.在这句话中，明天天气好是完全有可能实现的，并非虚拟，幻想，因此是真实条件句。在这个句子里面，应该采用“主将从现”原则。

（2）If I were you,I would go at once.在这句话中，条件句“如果我是你”只是假设的情况，没有实现的可能。因为事实上，我不可能成为你。当条件句实现的可能性很小，甚至可以说没有的时候，就要用虚拟语气，导致动词发生了变化。
三、真实条件句：
表示假设有极大的可能实现，常用引导词有：if, unless, once as, so long as, on condition that等等。注意：真是条件句常用主将从现结构，主句一般将来时，从句一般现在时，情态动词、祈使句、动词不定式（to do）都可以表示将来意思。
【例1】If I have time,I will come over to see you. （主将从现）
【例2】If the robot goes wrong,you can get a new one. （主情从现）
【例3】Don’t go to the movies if you don't finish your English reading. （主祈从现）
注意：
1) 在真实条件句中，主句不能用be going to表示将来，要用shall,will.
If you leave now, you are never going to forget it./ If you leave now, you will never forget it.
2) 表示真理时，主句谓语动词不用shall(will)+动词原形，而直接用一般现在时的动词形式。
四、虚拟语气：
1、if引导的条件句中的虚拟语气：
（1）对现在事实相反的虚拟：从句：谓语动词用一般过去时（did，be动词只用were）
主句：would/could/should/might + do（动词原形）
（2）对过去情况相反的虚拟：从句：用过去完成时had done（v.p.p）
主句：would/could/should/might +have done（v.p.p）
【典例1】（ ）If he hadn’t lost his money,he _____the piano last week.
A.would buy B.had bought C.could have bought D.bought
（3）对将来事实相反的虚拟：从句：谓语用should do,were to do或者动词的过去式（did）三种形式
主句：would/could/should/might+动词原形
（发生的可能性小，从句should do，译作“万一”）
【例句1】If I should fail,what should I do? 万一我失败了，我该做些什么？
【例句2】If he were to come, what should we say to him.
2、错综时间虚拟条件句（混合虚拟）：指条件状语从句表示的动作和主句表示的动作发生的时间不一致。在这种情况下，主句、从句的谓语动词的形式要根据各自表示的时间做出相应地调整。
（1）If I were you, I would have taken his advice. (从句指现在, 主句指过去)。
（2）If we hadn’t been working hard in the past few years, things wouldn’t be going so smoothly.（从句指过去，主句指现在）。
（3）If it hadn’t been for her care, I should not be speaking to you now.（从句指过去，主句指现在）。
（4）If we had not got everything ready by now, we should be having a more terrible time tomorrow. （从句指现在，主句指将来）  
【典例2】（ ）If I had seen the movie, I___ you all about it now.
A. would tell B. will tell C. have told D. would have told
3、虚拟条件句的倒装：虚拟条件句的从句部分含有were, should, 或had时，可省略if， 再把were, should, 或had移到从句的句首，实行倒装。
例如：Were they here now, they could help us. =If they were here now, they could help us.
Had you come earlier, you would have met him.=If you had come earlier, you would have met him.
Should he fail in the experiment this time,he would try again.=If he should fail in the experiment this time, he would try again.
【典例3】（ ）____to do the work,I should do it some other day. A.if I were B.I were C .Were I D.Was I
【典例4】（ ）___he finished the work, he would not have been punished. A.If B. Were C. Had D. Has
4、含蓄虚拟条件句：有时假设的条件不通过条件从句表示出来，而隐含在上下文或某些词或短语中，例如：but，or，otherwise，with，without，but for，supposing，for fear that等等。
（1）如果不是听了你的建议，我就不会做的如此成功。
But for your advice, I could not have done it so successfully. = If it had not been for your advice,…
（2）没有开放的政策，就不会有如此大的变化
The change could not have taken place without the open-door policy. = If it had not been for the...
（3）我当时很忙，否则，我就会把答案告诉他的。
I was so busy then, Otherwise, I would have told him the answer. = If I had not been so busy then,…
（4）What would I have done without you? (条件暗含在分词短语without you中)
（5）It would be easier to do it this way. (条件暗含不定式短语to do it this way中)
（6）We would have succeeded. (暗含if we had kept trying)
（7）This same thing, happening in wartime, would lead to a disaster. (条件暗含在分词短语happening in wartime中)
（8）Alone, he would have been terrified. (暗含条件是alone)
（9）I would have written long before, but I have been ill.(条件暗含在but的并列句中)
【典例5】（ ）But for the fact that the firefighters__at the spot in time,more people__their lives in the fire. A.arrived,lost B.had arrived,would lose C.had arrived,would have lost D.has arrived,would have lost
特殊地：从句可以使用if it were not for或had not been for构成谓语，表示若不是、要不是。
【例句1】If it weren’t for you help,we would not finish it in time.
【例句2】If it hadn’t for your help,we would have got into serious trouble.
5、特殊的虚拟语气词should
1) 在主语从句中的应用
It is demanded/ necessary/essential a pity + that… 等结构的主语从句，谓语动词用should+ 动词原形，should可省略。

It is
可用的词有三类

that

（should）do
suggested,ordered,required,proposed,demanded,requested,recommended, insisted
important,necessary,natural,essential, imperative,strange
a pity,a shame,no wonder
2) 在宾语从句中的应用
表示命令、建议、要求这一类动词：order，suggest，insist，require，advise，request，demand，decide，ask，propose，move，recommend，urge，desire(注意：insist如果翻译成坚持某种动作才用虚拟语气；翻译成坚持某种观点就不用虚拟语气。)谓语动词用should加动词原形或用动词原形，省略should。
【典例6】（ ）The English teacher suggested they ______widely after class.
A.would read B.will read C.ought to read D.read
【典例7】（ ）They ___our going to the zoo next Sunday.
A.insisted B.begged C.command D.suggested
一想要( desire)，一宁愿( prefer)，一坚持( insist)，二命令( order , command)，三建议( advise , suggest , propose/recommend)，四要求( demand , require , request , ask)中，无论主句谓语动词为何种时态，从句的谓语动词都用：" should + do"。should可以省略。
例如：He suggested that we (should) take the teacher's advice.
He insisted that we (should) take the teacher's advice.
He demand that we (should) take the teacher's advice.
He ordered that we (sh