单个情态动词分析.doc

单个情态动词讲解1.can(could)1).表示能力，意为“能，会”，用can, could, be able to均可，could是can的过去式。区别是：can只有过去时could，而be able to有多种时态。John can speak three foreign languages fluently. John could swim when he was four.I regretted that I hadnt been able to drive him home.Will you be able to help me learn English tomorrow? 明天你能帮助我学习英语吗？2）表示可能（理论上或是逻辑判断上）。Thetemperaturecanfallto60。气温可降至60Anybody can make mistakes.表示推测或可能性，常用于否定句和疑问句Can he be at school? Today is Sunday. He cant be at school.There is no light in the room. Can she have gone to bed?对过去的推测She could have gone out with some friends yesterday.It was silly to throw the TV out of the window. It could have hit somebody.You are late again. You could have got up earlier.3）表示请求或许可 （ Could 比 Can 更加客气，can比may更正式）Can I park my car in front of your office?CanIhavealookatyournewpen? Heaskedwhetherhecouldtakethebookoutofthereadingroom.Could I use your bike now? -Certainly. Go ahead. Yes, you can4）表惊异、怀疑、不相信等态度。主要用于否定句、疑问句或感叹句中。Wherecan(could)theyhavegoneto?他们会去哪儿了呢？Hecant(couldnt)beoversixty.他不可能超过六十岁。Howcanyoubesocareless?你怎么这么粗心？5）比较委婉客气地提出问题或陈述看法。Can(Could)youlendmeahand?帮我一把好吗？Imafraidwecouldntgiveyouananswertoday.恐怕我们今天不能给你答复。2. may and might 1) 表示可能性; 表不太可能的推测, might可以指过去时间，也可以指现在时间，但语气更加不肯定, may/might have done 对过去的揣测Helen may go on the trip with us, but she isnt quite sure yet.Theymightbehavingameeting,butImnotsure.He may be busy these days.Shemaynotknowaboutit.Hewasafraidtheymightnotagreewithhim.Your math teacher may / might be in his office.注意：用may表示推测一般不用于疑问句，在疑问句中通常用can来代替。 Can he be at home? 他可能在家吗？ Can it be true? 这可能是真的吗？ - It may be, or may not be. 2) 表示允许和请求 might不表示过去时，而是表示口气比较婉转。You may take whatever you like. 你喜欢什么就拿什么。He told me that I might smoke in the room. 他告诉我可以在房间里抽烟。May (Might) I ask for a photo of your baby? 我可以要一张你宝宝的照片吗？May I come in ? May I watch TV now? Yes, you may. May/ Might I have a talk with you? 我可以和你谈谈吗？ May/Might I come into the room to see my mother? - No, you mustnt. She needs to have a good rest.提示：May I . ?问句常见的肯定回答和否定回答。may引起的问句时，多避免用这个词，而用其它方式肯定回答Yes, please. / Certainly. / Yes, of course. / Sure. Go ahead, please.否定回答 No, you cant. (最常见)/ No, you mustnt.(具有强烈禁止的意思)Please dont. / Youd better not. / I dont think you can. / Im sorry its not allowed.3) 表示祝愿 May you succeed. 祝你成功 May you be happy. 祝你快乐。 May that day come soon.希望这一天早日到来。4）may/might as well Now that you are here, you may as well try your best. 还是的好 All the shops are closed; we may as well go back. You might as well speak out your mind. 你还是把你的想法说出来吧。 may well do sth. He may not well go with ushe hates travel.5）might用于虚拟 If he came here tomorrow, he might have a chance of talking with her.3. must and have to1）表示义务,意为“必须”= have to (must 现在；将来的必须 而且是主观看法 ,have to 有多种时态 而且强调客观情况)I really must stop smoking now.I had to leave early because I wasnt feeling well.Must I come here? Yes, you must. No, you neednt / dont have to - Must I get to the station before three oclock?- Yes, you must. ( No, you neednt. )2） must 表示推测 意思非常肯定 “一定是”“一定会”,不用于疑问句 must用于表示推测，它的肯定程度比may, might, could大得多，一般只用于肯定句。 (1) must do(这里的do通常是状态动词或系动词)表示对现在状态的推测。He must be very lazy, for his desk is very untidy. Carol must get very bored with her job. She does the same thing every day.He must be ill. He looks so pale.Shes wearing a diamond necklace. She must have a lot of money.He is absent today, and something must have happened to him.She must be at home now, as I just called her.(2) must be doing表示对现在动作或状态的推测。 Put on more clothes. You must be feeling cold with only a shirt on. 多穿点儿衣服，你只穿一件衬衣，肯定觉得冷。(3) must have done表示对过去的动作或状态的推测。He must have gone over the article, hasnt he?It must have rained last night, didnt it?The ground is wet. It must have rained last night. I didnt hear the phone. I must have been asleep. 提示must表示推测只用于肯定句，否定句和疑问句要用can, could来代替must。Hes just had his lunch. He cant be hungry already. 他刚吃过午饭，不会饿的。They have just arrived here. They cant know many people. Leslie walked past me without speaking. He cant/couldnt have seen me.3）用于指 偏要、硬要 （ 令人不快的事） The car must break down just when we were in the jungle. (偏要)- Could I have a word with you, mum? - Oh, dear, if you must. Who is the girl standing over there? - Well, if you must know, her name is Mabel. Why must it rain today? 为什么偏偏在今天下雨？When I was taking a nap, a student must knock at the door. 正当我午睡时，偏偏一个学生在这个时候来敲门。4)must可用来表示根据逻辑推理必然要发生的事，可译为“必然会，总是会”。We all must die. 我们都会死。 Truth must be out. 真相必然会大白的。Winter must be followed by spring. 冬天到了，春天还会远吗？4）禁止 (否定句)You mustnt make noises in the library. (禁止) (注：mustnt没有表推测的意思)must和have to的区别:1）must表示有做某一动作的必要或义务，强调主观看法，可译为“必须，应该”。. Everyone must obey the rule. We must do everything step by step. Teachers must be patient enough with their students.2） must含有说话者的强烈决意(表示主观的看法)，have to 则表示外力环境或习惯使然(即表示客观的必要，作“不得不”解)。I must study hard. 我必须努力学习。(发自内心的决定) I have to study hard. 我不得不努力学习。(外界因素逼迫) You must stay for supper. 你必须留下来吃晚饭(because I want you to) You have to stay for supper. 你得留下来吃晚饭。(because there is nowhere else to go)3 ) must只有一种形式，而have to可有多种时态。They had to put off the sports meet due to the bad weather. These last two days he has had to take a rest at home.4) must的否定式和have to的否定式的意思完全不同。You must keep it a secret. You mustnt tell anyone. (mustnt表示“禁止”) You dont have to tell me the secret. 你不必告诉我这个秘密。(dont have to意思是“没有必要”= dont need to)4.shall和should:1.shall (1) 疑问句中，表示征询意见或请求指示，用于一、三人称疑问句。Shall I carry it for you? Shall we sing a song?Shall they wait outside?Shall the waiter bring meals to your room?提示：Shall I open the window? 我打开窗子好吗？ Will you open the window? 你打开窗子好吗？(第二人称用will) Shall he open the window? 他打开窗子好吗？(2) 陈述句中，表示说话人的意愿，有“命令、强制，允诺、警告、威胁，决心”等意思，用于第二、三人称陈述句中。 You shall do as I say. No, he shant go.不! 他不能去。（表命令） He shall be sorry for it one day, I tell you.我告诉你，总有一天他会后悔的。(警告)You shall fall behind in your exam if you keep playing. Nothing shall stop us from carrying out the plan.什么也阻止不了我们执行这项计划。(决心) He shall have the book when I finish reading. 我看完这本书就给他看。(允诺) I shall do my homework after reading this story book. 读完这本故事书后我就做作业。You shall get the justice that you want.你会得到你想要的公平。（表允诺）You shall not use my camera if you dont use it properly.如果你不正确使用，我不会让你使用我的照相机（表警告）Nothing shall stop us from carrying out this plan.什么也阻挡不了我们实施这项计划。（表决心）2.should (1) 表示义务，意为“应该”(某件事宜于做)，用于各种人称。Children should obey their parents.儿童应该服从他们的父母。 One shouldnt be selfish. 人千万别自私。 Customers who get bad service should complain, shouldnt they? 没有得到满意服务的顾客应该抱怨，不是吗？You should be polite to your teachers. 你对老师应该有礼貌。 You shouldnt waste any time. 你不应该浪费时间。表示义务，意为“应该”(因责任、义务而该做)，口气比should稍重。 We ought to defend our country. 我们应当保卫我们的国家。You ought to respect your parents. 你应当尊敬你的父母。Oughtnt we to do everything possible to stop pollution? 难道我们不应当尽可能地制止污染?2）表推测，意为“想必一定、照说应该、估计”等表示对过去、现在或将来情况的某种推测 Thefilmshouldbeverygoodasitisstarringfirstclassactors 这部新电影是一流演员主演的，估计拍得很好。Theyshouldbehomebynow.照说他们现在应当已经到家了。It should be fine tomorrow. Its nearly seven oclock. Jack should be here at any moment. Should be doing 对现在的动作的推测 表应该做但却没做He should be taking a bath now.The boys shouldnt be playing football. They should be at school. Should have done 对过去的推测 表应该做但却没做You shouldnt have entered the teachers office without permission. 表示推测，暗含很大的可能，可译为“应该是，会是”。Prices ought to come down soon. 价格可能会很快下跌。Han Mei ought to know his telephone number. Theres a fine sunset; it ought to be a fine day tomorrow. 今天有晚霞，明天应该是个好天。ought to和should一样，表示对现在或以前应做的事却没做的责怪、批评。You ought to be washing your clothes. Why are you playing Ping-Pong?You ought to have handed in the exercise last week. 你上周就应当交练习。(可你没交，含责备的意思。)He ought to have asked me before he took my bike. 他在用我自行车之前应该和我讲一声。3) 常与what, how, why等词连用，表示意外、惊讶等情绪。 How should I know? 我怎么会知道呢?Why should I fear? 我为什么会害怕？ What should she do but cry for help? 除了呼救外，她还能干什么？ I dont know why you should think I did it. 我真不知道你凭什么认为这件事是我干的。should表示吃惊、赞叹、不满等情绪，也是近几年来的高考热点。Its wonderful that you should have achieved so much in these years.这几年你们有了这么大的成就真了不起。You cant imagine a gentleman like him should treat a lady so rudely.你想象不出来象他这样一位绅士竟然会如此粗鲁地对待一位女士。 4）ought to 与should的比较。ought to 和should的含义较近，但不完全相同ought to表示“应该”， 是从“义务”或“按理推断”的角度来讲的。should则是从说话人的个人看法这一角度来讲的。 You are her mother. You ought to look after her. 你是她的母亲，你应当照管她。(是道义上的责任，不能和should互换。) We should encourage him, for we are his classmates. 我们应该鼓励他，我们是他的同班同学啊！提示：表示“义务”时，我们在口语中可以用had better或be supposed to 来代替should和ought to。 If you are not well, you had better ask Alice to go instead. 如果你不舒服，你最好叫艾丽丝代替你去。Im supposed to be there at 8 oclock. 我应该八点到那里。5.will和would:1）will和would可用于第二人称疑问句，表示请求和建议等。would比 will委婉客气。Willyouclosethewindow?Itsabitcold. Wontyoudrinksomemorecoffee?再来一点咖啡好吗？ Will you have some tea? 你喝点茶，好吗？ Will you share your happiness with us? 你可以把你的欢乐与我们共享吗？ Would you pass this book to the student in the last row? 必背：Will / Would you . ? 表示请求和建议的答复。肯定回答 Yes, please. 是的，请。 Certainly. 当然可以。Sure. 当然了。All right. 好啊！否定回答Im sorry. I cant. 对不起，不行。No, thank you. 不，不行。No, I wont. 不，不行。比较： Would you like . ? 表示邀请 / Do you like .? 表示习惯 Do you like going/ to go the cinema? 你喜欢看电影吗？Yes, I go to the cinema a lot. 是的，我经常去看电影。 Would you like to go to the cinema tonight? Yes, Id love to. 非常乐意。2）will和would可表示意志、愿望和决心，用于各种人称陈述句。1）表意愿，用于各种人称陈述句。 I will do anything for you. I said I would do anything for you. He wont do what hes toldIll do my best . (意愿) I will never do such a thing again. (决心) I will never tell you the secret. 我永远不会告诉你这个秘密。 They would not let him in because he was poorly dressed. Theywouldnthaveanythingagainstit.他们不会有什么反对意见。3）will和would可表示推论或猜测。The patient took the sleeping pills an hour ago. He will be asleep now. 病人一小时前吃的安眠药，现在应该睡着了。 It would be about ten when he left home. 他大约在十点钟离开的家。 I thought he would have told you about it. 我认为他已告知你此事。 It would be raining when she went home. 她回家时可能正在下雨。It would be about ten when he left home. (表料想或猜想)3）will和would可表示某种倾向或习惯性动作。will表示现在的习惯动作，would表示过去的习惯动作 Fish will die without water. (习惯性、倾向性)He would be nervous when he met strangers. 遇见陌生人时他总是很紧张。In class he would ask some silly questions, and his classmates would laugh at him. 课上，他总是问一些蠢问题，他的同学们总是嘲笑他。Last year our English teacher would sometimes tell us stories in English after class. (过去的习惯动作,比used to正式，并没有“现已无此习惯”的含义。但used to表现在不做了)4）非情态动词的用法用于非人称主语时，表示物体的固有性质和倾向 This glass will not crack under heavy pressure. Fishwilldieoutofwater.鱼离开水就不能活。 Thedoorwontopen.这门打不开。Theboywillsittherehourafterhourlookingatthetrafficgoby. He promised he would never smoke again. (will的过去式)那男孩常常坐在那里好几个钟点，看着车辆行人通过。will表示将来时间时，不可用于条件状语从句，但will表示意愿或决心时，可用于条件状语从句。 If you will read the book, Ill lend it to you. If you will give up smoking, your health will improve. 6. need and dare 过去时 dared need 和dare一样，作为情态动词时，主要用于否定句和疑问句，一般不用于肯定句中(在肯定句中常被 must, have to, ought to, should等情态动词取代)。need和dare一样，也可以作行为动词，可用于肯定句、否定句和疑问句中。行为动词need有人称和数的变化。need1)need 情态动词 无时态；人称的变化 多用于疑问句和否定句作为情态动词，它的词形只有need一种形式。无过去式和单三形式You neednt return the book now. Need I hand in my homework now? 我现在就要交家庭作业吗？- Need he finish the article next week.- Yes, he must.- No, he neednt. (= he doesnt have to)-Need I come? -Yes, you must. -我需要来吗？ -需要。 You neednt telephone him now. 你现在不必打电话给他。 I dont think you need worry. 我想你不必发愁。neednt have done 本没有必要做，但是做了You neednt have waited for her, as