2017届高三英语一轮语法专项学案：第7节 情态动词和虚拟语气

　　第七节　情态动词和虚拟语气

　　(对应学生用书第252页)

　　考点一　情态动词的基本用法

　　1．can的用法

　　(1)表示能力。需注意的是，could表示过去一般的能力，而was/were able to表示有能力而且成功地做成了某事。

　　The fire spread through the building very quickly, but everyone was able to get out.尽管这场大火迅速蔓延了整个大楼，但是每个人都逃了出去。

　　(2)表示理论上的可能性，意为“有时候可能会”。

　　Everything can happen, everything is possible and probable.

　　任何事情都有可能发生， 没有什么是不可能的。

　　(3)表示请求和允许。在问句中，could比can语气要委婉。

　　—Could I use your bike? 我可以用你的自行车吗？

　　—Of course you can. 当然可以。

　　(4)表示推测，常用于疑问句和否定句。

　　What can they be doing there?

　　他们可能正在那里干什么？

　　He can't be in the classroom, for the light has been turned off. 他不可能在教室，因为灯已关了。

　　(5)can't/never ... too/enough表示“再……也不为过”。

　　You can never be too careful while driving a car. 开车时再小心都不为过。

　　2．may的用法

　　(1)表示请求、允许，此时might比may的语气更委婉。

　　—May/Might I play basketball this afternoon?

　　今天下午我可以打篮球吗？

　　—No, you may not. 不，不行。

　　(2)表示推测意为“可能、或许”。

　　We may go to the cinema tonight, but we are not sure yet.我们今晚或许去看电影，但还未确定。

　　(3)用于祈使句中表示祝愿。

　　May you be happy every day and succeed in your work! 祝你每天都过得开心且工作顺利！

　　(4)“may as well＋动词原形”意为“最好，倒不如”。

　　There is nothing to do, so I may as well go to bed. 没什么事可做， 我还是上床睡觉好了。

　　3．must的用法

　　(1)表示“必须；应该”，must一般指主观，而have to指客观表示“不得不”。

　　We must do everything step by step.

　　我们一切都必须循序渐进地做。

　　I have to go now for I've a meeting 15 minutes later.我必须走了，因为15分钟后有个会。

　　(2)表示推测意为“一定会”，此时不能用于否定句。

　　He must be ill. He looks so pale.

　　他一定病了，他的脸色苍白。

　　(3)mustn't表禁止，而have to的否定式意为“不必”。

　　Smoking mustn't be allowed in the office.

　　办公室里不许吸烟。

　　—Must we hand in our exercise today?

　　我们今天必须交作业吗？

　　—No, you don't have to. 不，不必今天交。

　　(4)表示偏执、固执意为“偏要，硬要”。

　　If you must smoke, please go out.

　　如果你硬要吸烟，那就出去吧。

　　4．shall的用法

　　(1)用于第一、三人称的疑问句中，用于征求对方的意见。

　　Shall I buy some picture books for the children? 要我给孩子们买些图画书吗 ?

　　(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、允诺或威胁；此外，当颁布法律、规定时也用shall。

　　You shall finish your homework first before you go out and play. 你得先做完作业再出去玩。

　　5．should的用法

　　(1)表示劝告和建议，意为“应该”。此时ought to比should语气要强。

　　You should/ought to put more effort into your work.你应该更加努力地工作。

　　(2)表示预测可能性，意为“按道理应该会”。

　　He left Paris in the morning. So he should arrive here by supper time.

　　他早上离开巴黎， 因此他晚饭前应该能到。

　　(3)表示惊讶、意外等情绪，意为“竟然”。

　　It is strange that such things should happen in our school.真奇怪，这样的事情竟然在我们学校发生了。

　　6．will/would的用法

　　(1)表示意愿，可用于各种人称。

　　We will never give up working, whatever happens. 无论发生什么事，我们都不会放弃工作。

　　(2)表示“请求；建议”，此时would比will更委婉。

　　Would you come into the bar and have a drink with me? 你愿意进酒吧和我喝一杯吗 ?

　　(3)表示习惯，意为“总是，习惯于”。与used to相比，would表示过去重复、习惯性动作；而used to则强调过去与现在的对比。

　　Last year our English teacher would tell us stories in English after class. 去年我们的英语老师常常课后给我们用英语讲故事。

　　He used to spend all his money on food and drink; now he lives a simple life.

　　他过去把钱都花在吃喝上， 现在可节省了。

　　7．need/dare的用法

　　need和dare既可作实义动词又可作情态动词，用作情态动词时，主要用于疑问句和否定句。

　　You needn't worry about him. 你不必为他担心。

　　She dare not go out alone at night.

　　她晚上不敢一个人出去。

　　考点二　 “情态动词＋have done”的用法

　　类型 构成

　　主要用法

　　表示对

　　过去的

　　推测 must have done 表示对过去发生的事情十分肯定的推测，意为“想必/准是/一定做过某事”。

　　can/could

　　have done 多用于否定句和疑问句，表示对过去发生的行为的怀疑和不肯定，意为“不可能已经……”或“可能已经……了吗？”。

　　may/might

　　have done 用于肯定句和否定句，表示对过去发生某事的可能性的推测，意为“或许做过某事”或“或许没做过某事”。

　　表示后

　　悔、责备

　　或遗憾 can/could

　　have done

　　用在肯定句中，表示对过去没有实现的可能性的遗憾，意为“本来能做……实际上却未做”。

　　should/ought

　　to have done 表示本该做某事而实际上未做；否定式表示本不该做但却做了。

　　needn't have

　　done 表示做了本来不必做的事。

　　The accident must have happened at about 11 o'clock in the morning.

　　事故一定是发生在上午11时左右。

　　He can't have gone to Shanghai, for I saw him a minute ago.

　　他不可能去了上海， 因为我刚才还看见他。

　　He might have said so at the meeting, but I'm not sure.他或许在会上说过这样的话，但我不确定。

　　You could have done better, but you didn't try your best.你本来能做得更好，但你没尽全力。

　　I was really anxious about you.You shouldn't have left home without a word.

　　我真的为你担心，你本不该不打声招呼就离开家。

　　You needn't have told him the news; he knew it already.

　　你不必再告诉他这个消息， 他已经知道了。

　　考点三　虚拟语气在非真实条件句的用法

　　说明 if从句谓语动词 主句谓语动词

　　与现在事

　　实相反 动词的过去式(be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 动词的过去式(be用were)/should＋动词原形/were to＋动词原形 would/should/ could/ might＋动词原形

　　If I were you, I would take action right away.

　　如果我是你，我会立即采取行动。

　　If you had got up earlier, you would have caught the train. 如果你早点起床， 你就会赶上火车了。

　　If you should fail, what would you do?

　　万一你失败了， 你准备怎么办？

　　考点四　虚拟条件的三种特殊形式

　　1．省略if的虚拟语气

　　如果if从句中含有were/had/should，则可以把if省略，把这三个词置于句首形成倒装。

　　Were it Sunday tomorrow, we should go to the Great Wall.

　　要是明天是星期日， 我们就能去长城了。

　　2．错综时间条件句

　　如果虚拟条件句的动作与主句动作发生的时间不一致，这时被称作错综时间条件句，动词的形式应根据它们各自表示的时间做出相应的调整。

　　If you had prepared in advance, you wouldn't be in such an awkward position now.

　　如果你事先做好准备， 现在就不至于那么被动。

　　3．含蓄虚拟条件句

　　有时假设的情况不是以if条件从句表示，而是通过其他形式表现出来，这时被称作含蓄虚拟条件句，其用法主要有三。

　　(1)用but for，without等介词(短语)表示条件。

　　But for the rain we should have had a pleasant journey.要不是下雨， 我们会有一次愉快的旅行。

　　(2)用连词otherwise，or等暗示后文与前面的情况相反，从而引出后文的虚拟语气。

　　There was a traffic jam on the way，otherwise I would have arrived an hour ago.

　　路上堵车， 要不然我一小时前就到了。

　　(3)虚拟条件通过but暗示出来，but前面为虚拟语气，后面为真实情况。

　　I should have given you more help, but I was too busy.我本该多帮帮你，但我太忙了。

　　考点五　虚拟语气的其他情况

　　1．用于宾语从句中

　　(1)wish后的虚拟语气

　　wish后宾语从句的虚拟语气有三种表达方式：

　　①过去时→表现在；②过去完成时→表过去；

　　③could/would/might＋动词原形→表将来。

　　I wish he were with us at this special moment.

　　我希望这个特殊时刻他和我们在一起。

　　How I wish I had followed my parents' advice.

　　我多么希望听了父母的建议。

　　She wished she would be admitted to Beijing University this year.她希望今年能被北大录取。

　　(2)用于表示要求、命令、建议、意图、决定、推荐等意义的动词：suggest, advise, propose, command, request, insist, recommend等后接宾语从句时，从句谓语动词为(should＋)动词原形。

　　He demanded that he (should) be told everything. 他要求将一切告诉他。

　　【点津】　当suggest表示“暗示，表明”，insist表示“坚持认为，坚持说”时，从句要用陈述语气。

　　Jane's pale face suggested that she was ill and we suggested that she (should) have a medical examination. 简苍白的脸色表明她病了，我们建议她做一下医学检查。

　　(3)would rather后的宾语从句，谓语用一般过去时表现在或将来要做的事情，用过去完成时表示过去的动作。

　　I'd rather that you came tomorrow.

　　我宁愿你明天来。

　　I'd rather that you had come yesterday.

　　你昨天来了该有多好。

　　2．用于主语从句、表语从句和同位语从句中

　　(1)表示要求、命令、建议、意图、决定、推荐等意义的动词，构成it is ＋动词的过去分词＋ that ...时，that从句中的谓语动词用(should＋)动词原形。

　　It is advised that the meeting (should) be put off until next week.有人建议会议推迟到下周举行。

　　(2)表示要求、命令、建议、意图、决定、推荐等意义的名词，如suggestion，proposal，advice，order，request等后面的表语从句和同位语从句中，谓语动词用(should＋)动词原形。

　　My request is that you (should) make an apology to your teacher.

　　我的要求是你要向你的老师道歉。

　　We all agreed to his suggestion that we (should) go out for picnic.我们都同意他的建议去野餐。

　　3．用于定语从句中

　　It's (high/about) time (that) ...句型中，从句的谓语动词用一般过去时或should＋动词原形(其中should不可省略)，句意为“确实到了……的时候了”。

　　It is high time that we took some measures to solve the problem.

　　确实到了我们该采取措施解决问题的时候了。

　　4．用于as if引导的从句中

　　表示与现在事实相反用一般过去时；表示与过去事实相反用过去完成时。

　　People treat him as if he were a dangerous person.人们把他看作是一个危险人物。

　　He talks as if he had been to many countries.

　　他说起话来好像他去过好多国家似的。

　　5．用于if only引导的感叹句中，其用法相当于wish后的宾语从句。

　　He failed in the exam again. If only he had worked harder.

　　他考试又失败了。要是他早努力些就好了。

　　(对应学生用书第255页)

　　Ⅰ.从下面方框中选择恰当的情态动词填空

　　shall，must，can，could，may，would，ought to，might，should1.________ you get a good result in your experiment!

　　2．________ you rather live in a town，or in the country?

　　3．________ we go to the new restaurant to have dinner?

　　4．You ________ leave your key at the reception desk.

　　5．A computer can't think itself.It ________ be told what to do.

　　6．The question comes down to whether we ________ act upon his advice.

　　7．Hurry up！He ________ be waiting for us anxiously right now.

　　8．My MP5 has disappeared.Who ________ have taken it?

　　9．—Where is Bob?

　　—He ________ be in the living room，but I am not sure.

　　10．You ________ not have told her the terrible news.She is very upset right now.

　　11．They are playing basketball；they ________ have finished their homework.

　　12．I saw him just now so he ________ not have gone abroad.

　　13．It's surprising that such a gentleman ________ be so rude to the old.

　　14．—May I watch TV after supper?

　　—No，you ________．

　　15．You look tired，so you ________ as well go and have a rest.

　　【答案】　1.May　2.Would　3.Shall　4.may/can　5.must　6.ought to/should　7.must　8.can/could

　　9．may/might/could　10.should　11.must

　　12．could　13.should　14.mustn't　15.may/might

　　Ⅱ.根据所提供的情景，用适当的情态动词完成句子

　　1．Marie called me up last night but I didn't hear it.I ________________________ asleep.

　　2．I can manage the shopping alone.You ________(not) come with me.

　　3．May be you ________ apologize to her，for she is sobbing bitterly in her room.

　　4．I am afraid of darkness and I ________________(not) go out alone at night.

　　5．The solider paid for the seat，when he ________________ entered free.

　　6．You ________ never be careful enough when you cross the road.

　　7．Even if he has time，he ________ go shopping in town on Sunday.

　　8．—How old are you，madam?

　　—If you ________ know，I'm twice my son's age.

　　9．—Tom must have lost his way，for he hasn't arrived yet.

　　—No，he ________________ lost his way.He has got a map with him.

　　10．I promise you ________ have the money as soon as I get it.

　　11．It's nearly time for class to start.The teacher ________ be here soon.

　　12．When she was a little girl，she ________ sit by the window every evening，deep in thought.

　　13．We ________________ received the letter yesterday，but it didn't arrive.

　　14．I really regretted wasting the hours when I ________________ studied hard，but it was too late.

　　15．Your home is not far from your school，so you ________________ left in such a hurry.

　　【答案】　1.must have been　2.needn't　3.should　4.dare not　5.could have　6.can　7.won't

　　8．must　9.can't/couldn't have　10.shall

　　11．should　12.would　13.should have　14.should have　15.needn't have

　　Ⅲ.根据汉语提示，用句末括号内的英语单词完成句子

　　1．要是他按照医生要求的那样静静地躺着，他现在就不那么受罪了。

　　If he had lain quietly as the doctor instructed，he ________________________ so much now.(suffer)

　　2．现在已经12点了，难道你不认为我们该回家了吗？

　　It's already 12 o'clock now.Don't you think it's about time we ________________？(go)

　　3．我昨天得了重感冒，否则，我就会完成作业了。

　　I had a bad cold yesterday，otherwise I ________________________ my homework.(finish)

　　4．要不是因为英语考试，我上周日就会去听音乐会。

　　But for the English examination，I ________________________ to the concert last Sunday.(go)

　　5．要不是因为她不会唱歌，我就邀请她参加聚会了。

　　If it ________________________ the fact that she can't sing，I would invite her to the party.(be)

　　6．即使太阳从西边升起，我对你的爱也不会变。

　　If the sun were to rise in the west，my love for you ________________________．(change)

　　7．仔细检查后，Michel的医生坚持认为他伤得很重，坚决要求他立刻动手术。

　　After careful examination，Michel's doctor insisted that he ________ badly wounded and that he ________________________________ at once.(operate)

　　8．如果不是空气吸收了太阳的部分热量，夜晚地球会非常冷，不适合我们居住。

　　Without the air to hold some of the sun's heat，the earth at night ________________________________ for us to live.(too)

　　9．我宁愿你明天去买书。

　　I would rather you ________________________________ tomorrow.(go)

　　10．他谈起话来好像他已经知道了这个秘密。

　　He talked as if he ________________ the secret.(know)

　　【答案】　1.would not suffer　2.went home

　　3．would have finished　4.would have gone　5.were not for　6.would not change　7.was；should be operated on　8.would be too cold　9.went to buy books　10.had known