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1、情态动词句型情态动词句型(高中英语复习)情态动词和不带to的动词构成谓语，有多种句型，是中学阶段语法要点。现将主要的由情态动词构成的句型归纳如下。1.must be / can not be：“must be”句型表示对现在状态的肯定推测，而“can not be”句型则是它的反义句型，表示对现在状态的否定推测。例如：She cant be forty.She must be fifty.（她不可能四十岁，她肯定是五十岁。）He cant be ill.He must be tired.（他不可能病了，他肯定是累了。）He must be an engineer.He cant be a do
2、ctor.（他肯定是位工程师，他不可能是医生。）It must be Wednesday today.It cant be Tuesday.（今天肯定是星期三，不可能是星期二。）It must be your tie.It cant be mine.（这肯定是你的领带，不可能是我的领带。）2.must be doing / can not be doing：“must be doing”句型表示对现在正在发生的动作的肯定推测，而“can not be doing”句型则是它的反义句型，表示对现在正在发生的动作否定推测。例如：He must be sleeping.He cannot be re
3、ading.（他现在肯定在睡觉，他不可能在看书。）They cant be listening to the radio.They must be watching television.（他们不可能正在听收音机，他们肯定正在看电视。）She cant be typing.She must be playing the piano.（她不可能正在打字，她肯定正在弹钢琴。）We must be driving at 50 miles an hour.We cant be driving at 60 miles an hour.（我们的车速现在肯定是每小时50英里，不可能是每小时60英里。）He
4、must be joking.He cant be serious.（他肯定在开玩笑，而不可能是认真的。）3.must have done：表示对过去的肯定的逻辑推测，推定某件事情、动作或状态可能在过去发生过（存在过）。He must have been a doctor, for he knows medicine so well.（他过去肯定是一位医生，他对医学如此了解。）Somebody must have stolen the ring.（肯定有人偷了这枚戒指。）该句所推断的偷窃动作发生在过去。The temperature must have dropped to below zer
5、o last night ,because the water is frozen all over.（昨夜的温度肯定降到零度以下，因为水都冻住了。）如果must + have + 过去分词句型与by now连用，还可以表示对现在完成的动作和状态的肯定推测，但实质上还是指所推测的过去的动作，例如：They started early this morning; they must have arrived by now.（他们今晨很早就出发了，现在肯定已经到了。）中国学生的常见病句是：They; they certainly have arrived.病句的句义是“他们当然已经到达了。”（这不
6、是对过去的肯定推测，而是断定动作已经完成。）4.can (could) not have done：表示对过去的动作或状态的否定推测，这是句型的反义句型。They cant have lost the way.Theyve been to the zoo before.（他们不可能迷了路，因为他们以前去过动物园。）He cant have been ill yesterday.He must have been tired.（他昨天不可能病了，他肯定是累了。）You cant have left your purse in the glass cabinet.You must have mis
7、laid it somewhere else.（你不可能把你的钱包放在玻璃柜里，你肯定把它错放在别的地方了。）It cant have been Wednesday the day before yesterday.（前天不可能是星期三。）句型和句型常常连用，例如：Two hours ago two visitors came to see you.They must have been American.They cant have been Russian.（二小时以前有两位来客要见你，他们肯定是美国人，而不可能是俄国人。）You must have mailed the letter.Y
8、ou cant have lost it.（你肯定已经把信寄了，而不可能把信丢了。）5.can / could have done：主要用于疑问句和感叹句中，could比can词义婉转，表示过去/现在完成的一种可能性推测。（注意：不一定肯定，有时还带有很大程度的否定推测。）Where can /could she have gone?（她会去了哪里？）How could he have forgotten me?（他怎么会忘记我？）句外之言：他不太可能会忘记我。How can /could he have done such a foolish thing?（他怎么会干出这种蠢事？）注意，如果
9、把上句的标点改为感叹号，意思大变，即：他怎么会干出这种蠢事！（表示气愤、谴责）could have done用于肯定句中表示过去有此能力，然而事实上并没有干，例如：He could have won the big prize, but he gave up the chance.（他本来可以赢此大奖，但是他却放弃了机会。）You could have done your work better.（你本来可以把工作干得更好。）这句话带有指责语气6.must have been doing：表示对过去进行或者过去完成进行的肯定推测。但是确切的时间概念却很难分清，因为过去进行的时间概念也包涵在过去
10、完成进行的时间概念里。At four oclock this afternoon you must have been watering the flowers in the garden.（今日下午四点钟，你肯定正在花园里给花浇水。）这是对过去进行的肯定推测You must have been driving at seventy miles an hour when that policeman waved to you.（那位警察向你挥手示意时，你肯定在以每小时70英里的速度开车。）I must have been dreaming when the teacher called me.
11、（老师叫我时，我的思想肯定在走神。）She didnt hear the telephone.She must have been sleeping.（她没有听见电话响，她肯定在睡觉。）7.can not have been doing：这是句型的反义句型，表示对过去进行或者过去完成进行的否定推测。I can not have been watching TV at seven oclock yesterday evening.I was attending evening school.（昨晚七点钟我肯定没有在看电视，我在上夜校。）这是对过去进行的否定推测句型和句型常有连用情况，例如：The
12、y cant have been listening to the radio.They must have been watching television.（他们那时不可能正在听收音机，而是肯定在看电视。）She cant have been cleaning the table.She must have been sweeping the floor.（她那时不可能正在擦桌子，而是肯定在扫地。）8.may have done：表示对过去的某一可能性的不确定的推测。注意，如果是肯定推测则用must have done，否则推测则用can not have done。Marys late
13、today.Well, she may have missed the bus.（她也许没赶上那班公交车。）He may have read about the traffic accident because its in todays newspaper.（他也许已看到那件交通事故消息，因为今日报纸有报导。）do you think my answer was right?Im not sure.It may have been right.（你那时的答案也许是对的。）We could not find John in the house.He may have been at a loc
14、al caf.（他也许在附近的一家咖啡馆里。）9.may have been doing：表示对过去进行或者过去完成进行的不确定推测：Do you think he was repairing the car?Im not sure.He may have been repairing the car.（我不敢肯定。他那时也许正在修理小车。）从上句可以推断，下句是对过去进行的不确定推测。Was she cleaning the plates?I dont know.She may have been cleaning the plates.（他那时也许正在洗盘子。）What had he be
15、en doing since eight oclock?Im not sure.He may have been painting the room.（他过去也许一直在油漆房间。）这是对过去完成进行的不确定推测。10.might have done：表示一种隐含的否定或者轻微的谴责。例如：Peter might have helped you if youd asked him.（如果你向彼得求助的话，他可能会帮助你的。）这是否定，意即：你并没有向彼得求助。You might have been more careful.Now all the plates are broken.（你应该小心一些，现在盘子都打碎了。）这是指责You might have given me at least a bouquet of flowers on Valentine Day.（你在情人节至少可以送我一束鲜花。）意即：那天你并
