高考情态动词用法.doc

情态动词：情态动词通常被用来表达说话人各种主观态度如命令要求，建议忠告，容许禁止，能力义务等：can和could的主要用法：1.表示能力或客观可能性。Humans cannot live on the earth without air or water.如果没有空气和水，人类就无法在地球上生存了。Can you finish this task within two days?你能够在两天内完成这项任务吗？2.could/can表示请求主要用于疑问句而不可用于肯定句，could语气委婉，其答语应用can。Could you show me how I can get to the post office in this town?你能告诉我如何到达这个城镇的邮电局吗？Yes, you can. （否定答语可用No, Im afraid not.）3.表示“可能”，用于猜测、判断、惊异、怀疑、不相信的态度。（主要用在否定句、疑问句或惊叹句中）“Can this be true?” the surprised man thought to himself.“那会是真的吗？”，那个人在自言自语道。The man working in the office right now cant be Mr Jackson.He is talking over there with my manager.正在办公室里工作的人不可能是杰克逊先生，他现在正在那边与我的经理谈话呢。4.“can(could)+have+过去分词”用于对某人现在已经完成的情况或过去具有的能力进行猜测或判断；其疑问或否定形式则表示完全否定的判断。如：Thomas could have taken the first place in the race,but unfortunately his leg was badly hurt.托马斯本来能够取得第一名成绩的，但不幸的是，他的腿在比赛中受了重伤。These people couldnt have known about the secret because it was only known by us two.那些人不可能知道这个秘密的，因为它只有我们俩知道。5.cannottoo/enough表示“无论怎样也不过分,越越好”。You must do this job carefully and you cant be careful enough when you do.你做这份工作必须细心，而且你越细心越好。Men love elegant women,so they cant be too elegant to a man.男人爱那些言谈举止温文尔雅的女人，她们越文雅越好。may和might的用法：1.表示请求、允许通常用于疑问句中，might比may的语气更委婉一些，否定回答时(口语中常用) no,you cant或 yes,please，用mustnt表示“切不可、千万不要”，含有禁止之意(具有强烈禁止的意思)。Might/May I open the windows to share the fresh air outside?Its a bit stuffy in here.Sure,go ahead.Im just about to open them.我可以把窗户打开呼吸一下新鲜空气吗？这里面有点闷热。当然可以，请吧！我正打算去打开它们。 Might I use your motorbike for an hour? No, you mustnt.Ill drive to pick up my daughter in the kindergarten soon.我可以用一小时你的摩托车吗？不行，我马上要骑车去幼儿园接女儿呢。用May I . 征询对方许可在文体上比较正式，在口气上比较客气。在日常口语中，用Can I . 征询对方意见在现代口语中更为常见。2.表示可能性的推测或判断，用于肯定句或否定句中，通常不用于疑问句。Miss Hunter may come to your birthday party this Saturday evening if you invite her.如果你要请她来的话，亨特小姐有可能星期六晚上来出席你的生日晚会。We can hear a lot of noise coming from the cinema.They may be holding a concert.我们听到影剧院里传来很大的嘈杂声，他们很可能正在举行音乐会。3.“may(might)+have+过去分词”表示对过去发生行为可能性的推测。Alice might have left the library when you called her with your mobilephone.你用手机打电话给她的时候，爱丽斯可能已经离开图书馆了。They have left here half an hour,so they may have arrived at the railway station by now.他们离开这里已经有半小时了，他们可能已经到达火车站了。must和have to的用法：1.must表示“必须、一定”，通常说明说话人的主观命令或强烈要求，用于肯定和疑问等各种句式中。We must get up before five tomorrow morning,or well miss the flight to New York.我们明天早晨必须在五点前期床，否则我们可能就赶不上飞往纽约的航班了。You mustnt smoke because smoking can worsen your disease.你千万不能抽烟，因为吸烟会使你的病情更加恶化的。回答must引出的问句时，如果是否定的回答，不能用mustnt，而要用neednt或dont have to。 Must we hand in our exercise books today? Yes,you must.(No, you dont have to.)我必须在今天交作业吗？是的，你必须。/不，你不必在今天叫来。2. must表示“肯定，一定”完全肯定的猜测或推测，它的否定或疑问式用can代替must。It must turn out to be fine this weekend.If so,we are going to climb the hill.这个周末天气肯定转晴天，要是这样的话，我们去爬山去。The light is still on in her room and she must be studying right now.她屋里的灯还亮着，她现在肯定还在学习。Can this schoolbag beWang Yans? Why did she leave it in the lab?这书包可能是王燕的吗？她为什么把书包放实验室呢？3. “must+have+过去分词”的结构常用在肯定句中，表示对过去发生的行为的推测。它的否定或疑问式用can代替must。He must have been to Shanghai before,otherwise he cant know about it so much.他以前肯定去过上海，不然的话他不会对上海了解那么多。They couldnt have talked about that problem at the meeting because they had already solved it.在那次会议上他们不可能讨论这个问题，因为他们此前已经解决它了。4. have to也用have got to，其含义与must相似，但have to有各种时态形式，随have的变化而定，往往强调客观需要或要求“不得已而为之”。Those poor orphans,most of whom were under twelve,had to work in the factory to support themselves.那些可怜的孤儿，大多数还不满十二岁，不得不在工厂干活来养活自己。Humans will have to find alternative energy to take the place of mineral resources人类不得不寻找可替代性能源来替代矿物能源。shall和should的用法1.Shall用于第一、第三人称疑问句中，表示说话人征求对方的意见或向对方请示。When shall we start off for the Hainan Island tomorrow?Youd better leave home before six.你看我们明天什么时候动身去海南好呢？你们最好在六点以前从家里出发。Lets play the game together,shall we?让我们一起去玩游戏好吗？Which room shall my mother be able to stay in the hospital?您看我母亲能够住在医院的那一间房子呢？2.Shall用于第二、第三人称的肯定句中，表示说话人给对方命令、警告、允诺或威胁。You shall fail if you dont work harder than before from now on. （警告）如果你从现在起在不更加努力的话你就会通不过考试了。He shall return the book to the library as soon as he finishes reading it. （允诺）他一看完这本书就得把它归还到图书馆。3.Should表示“应该，应当”，说明说话人的劝告、建议、命令，用于各种人称和句式中，其同义词是ought to。If you find someone around you in trouble,you should try your best to help him or her.如果你发现身边的人遇到麻烦，你就应该尽力去帮助他/她。Humans should pay attention to the worsening environment and do whatever we can to improve it.人类应该重视不断恶化的环境并且采取一切措施来改善环境。4.Should特殊用法，其含义较多用法较灵活，请看下面的句子：I should think it would be better to try it again. 我倒是认为最好再试一试。You are mistaken, I should say. 依我看，你是搞错了。I should advise you not to do that. 我倒是劝你别这样做。This is something I should have liked to ask you. 这是我本来想问你的。从以上例句可以看出：情态动词should用于第一人称时可以表示说话人的一种谦逊、客气、委婉的语气。5.Should还可以用在if引导的条件从句，表示一件事听起来可能性很小，但也不是完全没有可能,相当于“万一”的意思。虽然条件状语从句的谓语由should加动词原形构成，但是主句谓语却不一定用虚拟语气。Ask her to ring me up if you should see her. 你万一见到她，请让她给我打个电话。If you should change your mind, please let us know. 万一你改变主意，请通知我们。6.口语中引导条件状语从句的连词if常被省略而把should提到主语前构成部分倒装形式。Should it rain tomorrow,we would put off the sports meeting.万一明天下雨的话，我们就推迟运动会。Should I (If I should) be free tomorrow I will come.万一我明天有时间，我就来。7.在口语中，Why(or How) + should结构表示说话人对某事不能理解，感到意外、惊异等意思。意为“竟会”。如：Why should you be so late today? 你几天怎么来得这么晚？ Where is Betty living?？ How should I know? 贝蒂住在哪里？ 我怎么会知道呢？I dont know why you should think that I did it. 我真不知道你凭什么认为这件事是我干的。8. “should + have + 过去分词”结构一般表示义务，表示应该做到而实际上没有做到，并包含一种埋怨、责备的口气。Its a pity that I missed the train to Hangzhou.I should have got up earlier this morning.很遗憾我没能赶上去杭州的火车，今天早晨我本该早点起床的。You shouldnt have made so much noise in the night that your neighbours felt angry with you.你不应该在夜间制造那么大的噪音以致于你的邻居对你很不满。ought to的主要用法：1.Ought to表示“应该，应当”，说明说话人的劝告、建议、命令，用于各种人称和句式中，与其比should要更强烈。We ought to report the possible danger to the manager,which we found in examining the construction.我们应该把我们在检查建筑工程中发现的可能危险向经理汇报。You ought to obey every rule while working in the company,or youll be fired.你在公司工作期间应该遵守各种规章制度。2.表示“应该，应该”说明根据已有的事实或迹象进行分析作出的判断或猜测推测，单判断的语气肯定性不如must强烈。He must be at home by now. （断定他已到家）He ought to be home by now. （不十分肯定）This is where the oil must be. （比较直率）This is where the oil ought to be. （比较含蓄）3. “ought to + have +过去分词”表示过去应做某事而实际未做。You ought to have asked him (but you didnt).这时，ought to和should可以互相换用。相似情态动词用法辨析：must和have to表示“一定得，必须”：must通常用来说明说话者主观上的强调要求或命令，表示“必须，一定要”，其否定形式mustnt则用于强调禁止，表示“千万不要，切不可”; have to通常用来说明因外部客观情况或条件限制不得已而为之，表示“不得不，不得已”，其否定形式则用于说明不必要，表示“不需要”相当于neednt/dont need to。Must you leaving here right now?I wouldnt,but I have to prepare lunch for my children.你现在一定要离开吗？我不想离开，可是我得回