【步步高】2015届高考英语 语法专题七 情态动词和虚拟语气 外研版

专题七情态动词和虚拟语气◆情态动词的考查要点1．can，be able to 和could(1)can和be able to都表示能力，意思上没多大区别。

但can只有现在和过去时，而be able to则有更多的形式。

但当成功地完成某一具体动作时，通常不用could而用was/were able to来表示。

这时was/were able to 相当于managed to，表示经过一番努力，终于能够完成某事。

Her mother can speak French.The wounded man was still able to get to the village and was saved by the villagers in the end.(2)表示猜测“可能”，一般用于疑问句和否定句。

—Can the news be true?—It can’t be true.Someone is knocking at the door.Who could it be?(3)can可以表示理论上的可能性，指常有的行为或情形，意为“有时会……”。

Anybody can make mistakes.(4)表示请求、允许(表请求时，口语中常用could代替can使语气更委婉，回答时用can)。

Can I go now?—Could I come to see you tomorrow?—Yes，you can.(否定答语可用No，I’m afraid not.)(5)表示惊异、怀疑、不相信的态度(主要用于否定句、疑问句或感叹句中)。

How can that be true？I can’t believe my eyes and ears.How could you be so careless？！(6)can的特殊用法。

can but只有；can’t but不得不；can’t...too再怎样也不为过，越……越好I can but wait.I can’t but wait.You can’t be too patient to the customers.题组训练1用can，could，be able to的适当形式填空1．Though the building was on fire，they were able to go out safely.2．It can’t be the postman at the door. It’s only six o’clock.3．—How’s your new babysitter?—We could not ask for a better one. All our kids love her so much.4．The police s till haven’t found the lost child，but they’re doing all they can. 5．You can’t be too careful when driving.2．may和might的用法(1)表示允许、请求，might比may的语言更委婉一些。

—May I watch TV now?—Yes，you may.(Yes，please.)—No，you mustn’t.(No，you’d better not.)(2)表示可能性时，might比may的可能性小，may表示的可能性比can小(主要用于陈述句、肯定或否定句，疑问句用can代替)。

The story may not be true.(3)表示祝愿(不用might)May you succeed!(4)may/might as well最好还是……，不妨You might as well do it now.(5)may/might well很可能He may well be late for class.题组训练2用may，might的适当形式填空1．—I don’t really like James. Why did you invite him?—Don’t worry. He might/may not come. He said he wasn’t certain what his plans were.2．—I left my handbag on the train，but luckily someone gave it to a railway official. —How unbelievable to get it back! I mean，someone might have stolen it.3．As a student，you might/may as well make good use of your time.4．You may go to school either by bike or by bus.5．May she rest in peace.3．must，have to和ought to的用法(1)must表示“必须，应该，一定要”。

强调主观看法，只有现在时形式，否定式是must not(mustn’t)。

must开头的问句，其否定回答要用needn’t或don’t have to代替。

(2)must表示必然的结果。

All men must die.(3)must还可表示主语固执、偏要做他人不希望做的事。

It can’t help；he must do that.(4)have to着重客观需要，能用于更多时态(过去时或将来时)。

He will have to be there before ten.(5)ought to表示义务和责任，“应该”，比should语气要强。

You ought to take care of yourself.4．need和dare的用法(1)need表示“需要，必要”，只能用于否定句和疑问句。

在肯定句中，常用must和have to 代替。

(2)dare表示“敢”，通常用于否定句、疑问句和条件状语从句中。

Dare you go home alone at eleven in the evening?(3)need和dare的特殊用法①need表“需要”时，可用want，require代替。

The desk needs to be repaired./The desk needs repairing.②dare作实义动词时，在肯定句中要接to，在疑问句和否定句中to可省去。

He dares to catch a snake.I do not dare (to) complain.Do you dare (to) swim in the river?题组训练3同义句改写1．He daren’t go out at night.He doesn’t dare to go out at night.2．The flowers need watering.The flowers need to be watered.5．will和would的用法(1)will①表示请求、建议，常用于第二人称。

Will you please go with me?②表示意愿、决定、允许。

I will never do that again.③表示习惯性动作或某种倾向，“总是，惯于”，通常用于第三人称。

Rosa will always be late for school.(2)would①表示请求、建议，比will委婉，指现在时间，多用于第二人称。

Would you like a cup of tea?②表示过去习惯性动作或某种倾向。

We would play badminton on Sundays.6．shall和should的用法(1)shall用于第一、三人称，在问句中表示征求对方意见或请求。

Shall I come in?用于第二、三人称的陈述句中，表示命令或威胁。

You shall do as your father says.(2)should①表示责任、义务，意为“应该”。

②表示惊讶语气，意为“竟然”。

You should wear slippers in class.③用于条件句，表示“假如，万一”，省去if，should可提至句首。

Should you be late，apologize to the teacher.7．情态动词表示推测或判断的用法下表即是表示推测的情态动词使用的场合：情态动词对现在和未来的推测对过去的推测使用场合must must＋do must have done 肯定句may/might may/might＋do may/might have done 肯定句、否定句can/could can/could do can/could have done 否定句、疑问句(could可用于肯定句)should 用来表示一种估计的情况“按理会/估计会”should doshould have done 肯定句、否定句、疑问句情态动词＋have done的用法(1)should have done表示“本来应该做某事而实际上未做”，而shouldn’t have done 则表示“本不应该做某事而实际上做了”。

You should have told me about it earlier.You shouldn’t have said such words to your parents.(2)ought to have done也表示“本应该……”，而ought not to have done则意为“本不应该……”。

You ought to have told me about it earlier.You ought not to have said such words to your parents.(3)needn’t have done表示“本无必要做某事而实际上做了”。

You needn’t have walked so quickly since time was enough.(4)could have done表示“本来有可能……而事实上未做到”。

I could have come on time，but my car broke down on the way.(5)may/might have done表示“过去可能发生过某事”或“本来应该或可以做某事(实际上没做)”。

You might have given him more help, but you were so busy.题组训练41．I could have helped you(我本来可以帮助你的)，but I was too busy then.2．It’s Sunday. He can’t have gone to school(不可能上学去了)．3．You know the story very well. You may/might have read it(可能读过) before. 4．You must have gone to bed late(一定是睡得很晚) last night. Your eyes are red. 5．I should/ought to have done my homework(本应该做作业) last night，but I went to the cinema.◆语法填空AOne of the many things we take for granted in the twentieth century is the speedy collection and delivery of letters to and from all parts of the world at astonishing cheap rates.A husband away 1.on a business trip can write to his wife two thousand miles away knowing that the letter will reach 2.her in a few days.His special air­letter may cost him less than 3.a loaf of bread or his own bus fare to work.This service，however，is a favor of comparatively recent origin.Until modern times the cost of sending letters privately was so great that the 4.arrival(arrive) of a letter was a considerable event and might even cost financial hardship to the receiver 5.who/that had to bear the charges.6.From the Middle Ages on，there were indeed special messengers 7.carrying(carry) state correspondence，and other messengers employed to travel with news between the great monasteries or the great merchants’ houses，but for centuries there was no official post service by which private letters could 8.be sent(send)．It was not until 1840 9.that the official organization known as the Penny Post 10.was established(establish) in Great Britain and gave ordinary people cheap and efficient postal deliveries.BIt’s important to learn some knowledge about first aid in our daily life.If a person has an accident they need some medical care before a doctor can be found.When 1.you give first aid，you must pay attention to three things：Firstly，when a person 2.stops(stop) breathing，open their mouth 3.to see(see) if there is food at the back of their mouth.Secondly,4.if a person cannot breathe，do your best to start their breathing at once，using a mout h­to­mouth way.Thirdly，if a person is hurt badly，try at once to stop the bleeding，then take them 5.to a doctor.Many accidents may happen at home，all parents should know how to deal with common 6.injuries(injure) which may happen to their children.When a child 7.is bitten(bite)by an animal，wash the wound with cold running water.When a child is burnt，wash and cool the area of the skin 8.under the cold tap for a while,9.and then put a piece of dry clean cloth over the burn.Knowing about some first aid somet imes can save 10.a person’s life.◆虚拟语气的考查要点1．虚拟语气用于条件状语从句(1)表示与现在事实相反的假设，条件状语从句中的谓语动词用一般过去时(be动词用were)，而主句中的谓语动词用“would/should/could/might＋动词原形”。