情态动词专题讲义.doc

情态动词一 情态动词的类型和特征1 情态动词的类型（1）只做情态动词的有:can (could),may (might)（2）可以做情态动词也可以做实意动词:need（3）可以做情态动词也可以做助动词:will(would),shall(should)（4）具有情态动词的某些特征的有have to, ought to.2 情态动词的特征（1）有一定的意义，但不能单独做谓语，必须和行为动词或者系动词连用，构成谓语。（2）无人称和数的变化（have to 例外，第三人称单数时候用has to）.She has to stay here.她不得不呆在这里。（3）后边接动词原形She may lose her way。 她可能迷路了。（4）具有助动词的作用，可以构成否定句、疑问句、以及用于简明回答。-Can you sing an English song?-Yes, I can .二 情态动词的用法考点一：can，may，must等情态动词在陈述句中的用法：1. can的用法：（1）表示能力，一般译为“能、会”，即有种能力，尤其是生来具备的能力。如：She can swim fast, but I cant . 她能游得很快，但我不能。I can see with my eyes.我用眼睛看。（2）.表示许可，意为“可以”，常在口语中。如：You can use my dictionary. 你可以用我的字典。You can go。你可以走了。（3）.表示推测，意为“可能”，常用于否定句和疑问句中，此时cant译为“不可能”。如：Can the news be true?这个消息会是真的吗？Can it be our teacher? 那个人有可能是我们老师吗？No, it cant be our teacher. He is on a visit to the Great Wall.不可能。咱们老师正在游览长城呢。Li Hua can not be in the classroom.李华不可能在教室里。【例题】I think Miss Gao must be in the library. She said she would go there.No. She _be there, I have just been there.【解析】根据下文“我刚去过那儿”可知，应为“不可能”，cant表示推测答案 2. could的用法：（1）can的过去式，意为“能、会”，表示过去的能力。如：He could write poems when he was 10. 他十岁时就会写诗。（2）could在疑问句中，表示委婉的语气，此时could没有过去式的意思。如:Could you do me a favor？ 你能帮我个忙吗？Could I use your pen? 我能用一下你的钢笔吗?Yes, you can.可以。（注意回答）3. may的用法：（1）表示请求、许可，意为“可以”，比can正式，如：May I borrow your bike?我可以借你的自行车吗？You may go home now.现在你可以回家了。May 表示请求时，用于主语为第一人称的一般疑问句，其否定回答用 mustnt,不用may not，意为“不可以，不许，禁止”。如： -May I go now? 我现在可以走了吗？ -No，you mustnt。不，不可以。【例题】_ I borrow your MP3?Sure. Here you are. A. May B. Should C. Must D. Would【解析】在此处表示请求，意为“做可以吗”。答案：A (2) 表示推测，谈论可能性，意为“可能，或许”，一般用于肯定句中。如：It may rain tomorrow .明天可能会下雨。She may be at home.她可能在家呢.He may come tomorrow? 明天他可能会来。(3) 表示希望、祈求、祝愿，常可译为“祝愿”。通常是用may +主+V例如：May you have a good time.祝你过得愉快。May you be happy! 祝你幸福！May you succeed！祝你成功！4. must的用法：(1)must表示主观看法，意为“必须、一定”。如：You must stay here until I come back.在我回来之前你必须呆在这儿。Must I hand in my homework right now? 我必须现在交作业吗？（2）对must引导的疑问句，肯定回答为must，否定回答或neednt ，相当于dont have to .表示“不需要，不必”。如：Must I finish my homework?我现在必须完成作业吗?- Yes, you must.是的，必须。-No, you neednt.不，不必。 (3)must表示有把握的推测，用于肯定句。如: The light is on, so he must be at home now.灯亮着，他现在肯定在家。（4）含有must的反意疑问句。陈述部分含有must，且表示“必须”时，反意疑问句部分用mustnt。陈述部分含有must，且表示“必要”时，反意疑问句部分用neednt。We must stay at home, mustnt we? （必须）我们必须留在家里，是不是？They must take medical lessons, neednt they? (必要)他们一定要上医学课，是吗？5. need的用法：（1）need表示需要、必须，主要用于否定句和疑问句中，意为“没有必要，不必”。用need提问时，否定回答dont have to或者neednt。如：Need I stay here any longer? 我还有必要留在这儿吗？Yes, you must .是的。No. you dont have to.（No，you neednt。）不，你不必。(2).need还可以作实义动词，此时有人称、数和时态的变化，如果是人作主语后边多接动词不定式。如：I need to do it right now.我需要马上做这件事。He needs to learn more about the girl.他需要多了解那个女孩。如果是物作主语，一般用need doing与need to be done这种情况下应注意两点：.主动形式的动名词doing具有被动的含义；.该动名词可以改为其动词不定式的被动形式而句子的意义不变。例如：. The door needs painting. = The door needs to be painted.那扇门需要油漆一下。Your car needs mending. = Your car needs to be repaired.你的车需要维修了。6 shall的用法：shall用于第一人称表示征求意见、询问。如：Shall I open the window？我打开窗户好吗?Shall we have lunch here? 我们在这儿吃午饭好吗？Shall we go out for a walk? 我们出去散步好吗？比较记忆在英语中，我们可以用其他多种方式提出我们的建议或征求对方意见。（1）用“Lets do.”来提出建议。如：Lets go for a walk after supper.(2).用“What/How about.?”来提出建议；about后接名词或动词ing形式。如：What about/How about a drink? What about/How about taking Tom with us?(3).用“Why not.?”来提出建议，表示“何不”not面后接动词原形。“Why not.?”实际上是“Why dont you/we.?”的简略形式。如：Why not meet at the school gate at eight? Why dont we stay here another day?(4).用“Would you like.?”来提出建议，意思是“你想要吗?”Would you like后可接名词或不定式。如：Would you like a cup of tea?Would you like to go and see her?因此，如果我们说：“去游泳好吗?”英语中可有这样几种表达法：Shall we go for a swim?Lets go for a swim，shall we?What about/How about going swimming?Why not go for a swim?Would you like to go for a swim?What do you think of going for a swim?7. should的用法：（1）should意为“应该”，可表示劝告、建议、义务、责任等。如：We should protect the environment.我们应该保护环境。（2）Should have done表示对过去动作的责备、批评。如：You should have finished your homework.你应该已经完成作业了。（事实上你没有完成。）8. will的用法：will表示意愿、意志、打算，可用于多种人称。如：I will help you if Im free this afternoon.今天下午如果我有空，我就会帮你。Will you pass me the book？把那本书递给我好吗？We will do everything for you。我们会为你做任何事情。注意：1、will在there be句型中的形式及其句式变换。由于“一般将来时”的结构可以用“will+动词原形”来表示，所以there be句型的一般将来时的形式就是there will be。（一定不能说there will have）例如：There are many students in our school. There will be many students in our school. There will be a sports meeting next week.一定不能说：There will have a sports meeting next week.2、will与be going to do something区别：. be going to表示近期、眼下就要发生的事情，will表示的将来时间则较远一些，如：He is going to write a letter tonight. He will write a book one day. be going to表示根据主观判断将来肯定发生的事情，will表示客观上将来势必发生的事情。He is seriously ill. He is going to die. He will be twenty years old. be going to含有“计划，准备”的意思，而will则没有这个意思，如：She is going to lend us her book.He will be here in half an hour.在有条件从句的主句中，一般不用be going to,而多用will,如：If any beasts（野兽） comes at you, Ill stay with you and help you。9 would的用法Would表示过去的意愿或者委婉的询问Would you tell me the way to the station？你能告诉我去车站的路吗？10. had better的用法：“had better + 动词原形”表示最好做某事，否定式为 had better not。如：We had better go now.我们最好现在就走。You had better not give the book to him.你最好不要把这本书给他。考点二：含有情态动词的疑问句的回答:1.对may引出的问句，可以有下列回答方式：Yes, you may. Yes, of course.Yes, certainly.Sure . No, you cant.2.对must引出的疑问句，回答方式为：Yes, must. No,neednt。3.could在疑问句中，表示委婉的语气，此时could没有过去式的意思。如:Could I use your pen? 我能用一下你的钢笔吗?Yes, you can.可以。（注意回答）4. shall引出的疑问句用于第一人称，表示征求对方意见或客气的请求。其回答方式有以下几种：Yes, please.All right.No, thank you.5. would you的回答方式有以下几种：Yes, I will. (No, I wont.)。Sure . (Im sorry , I cant.)All right/ OK/ With pleasure. Certainly. (No, thank you .)Yes, please.【例题】Would you bring me thanks to Lily?_.A. Thats right B. With pleasure C. No trouble【解析】A.意为“对了”，B.意为“乐意效劳”, C.意为“没关系” D.意为“不费事”。答案：B考点三:不同情态动词的否定意义也不同：1.（1）.cant可译为“不会”，如：I cant play basketball.我不会打篮球。（2）当句子表推测时，用cant表达不可能，如：He cant be ill. He is playing chess with Tom.他不可能病了，他正和Tom下棋呢。（3）cant还可用来回答“ May I ? ”这样的问句。如：May I come in ? 我可以进来吗？No, . / cant.不，你不能。（4）cant还可用于固定习语中。cant help doing禁不住，情不自禁cant wait to do something迫不及待地要做如：She cant help crying.她不禁大哭起来。The children cant wait to open the box.孩子们迫不及待地想打开盒子。2. may的否定式为may not，译成“可能不”，如：He may not be at home.他也许不在家。考点四:情态动词的被动语态含有情态动词的被动语态的结构为：情态动词+ be + done (动词的过去分词)。做题时要兼顾情态动词和被动语态这两个方面。She should speak to her mother in that way.她不应该用那种方式和妈妈说话。More and more trees must be planted in China.在中国必须种植更多的树木。Many of the stars can not be seen because they are far away from us.很多星星我们都看不到，因为它们离我们太远了。考点五:情态动词表示推测的用法:一、“情态动词+动词原形”表示对现在的推测。1、can表示推测时一般用于否定句或疑问句。如：That man cant be her husband, she is still single.Who is knocking at the door?Can it be the postman?2、must表示肯定的推测，一般用于肯定句中。如：He must be in his office now. Mr. Li must be working now，for the lights in his office are still on.3、might表示推测时不一定是may的过去时，只是表示其可能性较小。如：The man may be the headmaster.Where is Mr. Li?He might be working in his office. May Mr. Li come?He might not come here.4、Could表示推测时，语气can比要弱，说话者留有余地。如：Could it be an animal?It could not be，because it is not moving.5、Should表示推测的可能性比较大，仅比must的可能性小一点。如：It is already 10 oclock now they should be there.【情态动词易混点归纳】易混点一: can和be able to:两者表示能力时用法相同，但can只有原形“can”和过去式“could”两种形式，在其他时态中要用be able to来表示。另外be able to常常指经过努力，花费了时间和劳力之后才能做到某事。如：Jim cant speak English.吉姆不会说英语。He could speak English at 5.他五岁时就会说英语。Well be able to see him next week.下星期我们将会见到他。He has been able to drive.他已经会开车了。Im sure youll be able to finish it quickly.我相信你能迅速地完成。We were able to reach the top of the mountain at noon.我们能在中午到达山顶。易混点二:can和may1. can和may均可用来征求意见或许可，意为“可以”，一般可互换使用。如：Can/ May I help you ? 我能帮助你吗？2. can和may表示可能性时的区别：1)在肯定句中用might，may，must，不用can2)在疑问句中表示推测用can，不用might，may，must3)在否定句中用cant（不可能），不用may，must。如：She may be in the classroom .她可能在教室里。Where can they be now?他们现在可能在哪儿？That cant be true.那不可能是真的。易混点三: may be和maybe 用法区别 常用位置may be may为情态动词，be为动词原形 句中，作谓语maybe 副词，大概、也许，相当于perhaps 句首，作状语例如：He may be wrong , but Im not sure.也许他错了，但我也不确定。易混点四：cant和1. cant根据其基本用法可译为：（1）不会。如：I cant speak English .我不会说英语。（2）不能。如：We cant do it now because its too dark.天太黑了，我们现在干不了。（3）否定句中表示推测。“不可能”，如：The man cant be our teacher because he is much younger than our teacher.那个人不可能是咱们老师，他年轻得多。易混点五：must和have to1.must侧重于个人意志和主观上的必要。have to侧重于客观上的必要，可用于现在时、过去时和将来时。如：I know I must study hard.我知道我必须努力学习。My brother was very ill, so I had to call the doctor in the mid-night.我弟弟病得厉害，我只得半夜里把医生请来。I havent got any money with me, so Ill have to borrow some from my friend.我身上没带钱，只好向朋友借点了。He said they must work hard.他说他们必须努力工作。2. have to可以用于多种时态；而must只用于一般现在或将来。如：The composition is due to hand in this morning, so I had to finish it last night.作文今天早晨到期，因此我不得不昨天晚上完成。易混点六: used to do / be used to doing / be used to do/ be used for doing used to do表示过去常常发生的动作，强调过去，只用于过去，注意用to do，不用doing形式；而be used to doing意为“习惯做”，be可有各种时态；be used to do意为“被使用去做,”为被动语态形式。be used for doing 用作”如：My father used to eating meat.我父亲过去起床晚，但现在不得不早起了。She is used to eating meat.她习惯吃肉。He wat used to eating in a restaurant.他不习惯在饭店吃饭。A knife can be used for cutting things.(刀可以用来割东西)/ A knife can be used to cut things.(刀可以用来割东西)历年真题1 - you turn down your radio, please? -Yes, I can.A. May B. Need C. Must D. Can2 -Can I wear any clothes I like to school? -No, you cant. You _ wear a uniform.A. might B. must C. will D. would3 Everyone _ go through the security check when entering the World Expo Park.A. can B. may C. must D. ought4 -Must I clean the room now?-No，you _ .You can do it tomorrow.A. mustnt B. must C. neednt D. need 5. It is the library! So you _ know shouting is not allowed here.A. can B. must C. need D. may 6 -I saw Kevin in the supermarket this morning.-No, it _ be him . He moved to Canada last week.A. can be B. must be C. cant be D. mustnt be7 -Look at the girl! Is it Susan? -No, it _ be her. She has gone back to her hometown. A. mustnt B. cant C. neednt D. wouldnt8 Im feeling better now so you _ call the doctor.A. couldnt B wouldnt C. cant D. neednt9. - This desk is too heavy. I _ move it. Can you help me. - No problem.A. can B cant C. should D. shouldnt10 - This lake is said to be dry, Is that true ?-It _ . Look ,some kids are swimming in it.A. must be true B. cant be trueC. may not be true11 -Dad, must I do my homework now? - No, you _ play games with your friends for a little while.A. would B. neednt C. may12 - What will the weather be like tomorrow? -It _ be rainy, cloudy or sunny. Who knows?A. must B. might C. shall D. should13 - How was the youth club last night, Mark? -It was great fun. You _ come. A. must B. can C. should D.may14 - _ your American friend eat with chopsticks? - Yes , but he cant use them well.A. Can B. Should C.Must答案与解析：1D -你能把收音机声音调低一些吗？ -好的，可以。由答句“yes，I can。”可知答案为D。2. B -我可以穿我喜欢的任意