情态动词 (3).doc

情态动词知识梳理情态动词有具体的词义，但也同助动词一样，需要与其他词语一起构成句子的谓语，另外情态动词没有人称和数的变化，情态动词后必须跟动词原形。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、许可、可能性。 表示能力时一般译为“能、会”， 即有种能力，尤其是生来具备的能力，此时may 和must 均不可代替它。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，常在口语中。如：You can use my dictionary. 你可以用我的字典。（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。注意：can 用于肯定句，表示理论上的可能性，即事件或情况可能发生但并不涉及是否真的发生，译为“有时会”，如：Driving on the snowy roads can be very dangerous .【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. A.cant B.mustnt C.neednt D.wouldnt2. 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 favour? 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，表示给予允许，一般只用can）你知道can / be able to 的用法区别吗？ 3. may/ might的用法：（1）.表示请求、许可，比can 正式，might 的语气更加委婉。如：May/ Might I borrow your bike? 我可以借你的自行车吗？-Yes,you may. （注意回答，表示给予允许，一般只用can）You may go home now. 现在你可以回家了。【例题】( ) _ I borrow your MP3? Sure . Here you are. A. May B.Should C.Must D. Would(2) .表示推测，谈论可能性，意为“ 可能， 或许”，一般用于肯定句和否定句中。 如：It may rain tomorrow . 明天可能会下雨。She may be at home. 她可能在家呢.比较： cant 不可能 It cant be true .may not可能不 It may not be true .(3) may的过去式为might ，表示推测时。可能性低于may。 如：He is away from school. He might be sick.他离开学校了，可能是他生病了。你知道may be /maybe 的用法区别吗？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) 其否定形式mustnt表示“ 一定不要 ” “千万别” “禁止, 不许”. 如：You mustnt play with fire. 你不许玩火。You mustnt be late. 你一定不要迟到。（3）对must引导的疑问句，肯定回答为must，否定回答为neednt 或 dont have to .如：Must I finish my homework?我现在必须完成作业吗？No, you neednt.不，你不必。(4)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。你知道must/ has to 的用法区别吗？ 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，其否定形式为neednt，意为“没有必要，不必”。 用need 提问时，肯定回答为 must，否定回答为 neednt或dont have to。 如： Need I stay here any longer? 我还有必要留在这儿吗？Yes, you must .是的。No. you neednt /dont have to. 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。6. dare 的用法：dare意为“敢、敢于”, 用法近似于need，有两种词性：（1）dare 作为情态动词，多用于否定句、疑问句或条件句中，无第三人称单数形式，只有一般现在时和一般过去时。如：Dare he tell them what he knows? 他敢告诉他们所知道的情况吗？I darent ask her this question . 我可不敢问她这个问题。（2）dare 作为实义动词，此时有人称、数及时态的变化。如：He doesnt dare to break his promise.他不敢食言。7. shall 的用法：shall表示征求对方意见（多用于第一、三人称）. 如：Shall we go out for a walk? 我们出去散步好吗？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?8. should /ought to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) ought to (= should)否定形式：ought not to / oughtnt to 一般疑问形式 将ought 提前。 People ought to stop polluting the environment .9. will/would 的用法：will表示现在的意愿、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。would表示过去的意愿、意志、打算。如：The doctor said he would fight against SARS until his end of life.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 sth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 in the future . 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. And 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 come 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 it doesnt rain tommorrow, Ill go to the park with you .10. had better 的用法：had better 意为“最好”，没有人称的变化，后面接不带to 的不定式，其否定形式为：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: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, you mustnt. / 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 sth 迫不及待如：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。3.（1）mustnt 表示不许，不可。如：He mustnt leave his room. 他不许离开他的房间。You mustnt talk in class. 你们不可以在课上说话。(2) mustnt 也可用于以 may 表示要求时的否定回答中。如：May I stand here? 我可以站在这里吗？No, you mustnt (cant). 不，不行。4.（1）neednt 意为“ 不必”。如：You neednt meet him unless youd like to.你不需要见他，除非你愿意。5. shouldnt 表示不应该。如：You shouldnt feed the goldfish so much food .考点三: 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. 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. 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.【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: 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。 Maybe he is 30 years old . = He may be 30 years old .易混点三：cant 和 mustnt1. 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。2. mustnt 意为“ 禁止、不许”， 用来表达命令，表示强烈的语气。 如：You mustnt play football in the street. Its too dangerous.你不可以在街上踢足球，太危险了。易混点四：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。2. 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。2. have to可以用于多种时态；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。His mother is ill, so he has to look after his mother at home .【情态动词例题解析】1、_ you pass me a pen? Id like to write down the phone number. Sure. Here it is.A. Can B. Need C. Might D. Must2、May I go to the cinema, mum? Certainly, but you _ be back by 11 oclock.A. can B. may C. must D. need 3、You _ get there by bus. A. dont need B. neednt to C. dont need to D. need dont to4、You _ worry about me. Its nothing serious. A. cant B. mustnt C. neednt D. wont5、Excuse me. Is this the right way to the Summer Please? Sorry, Im not sure . But it _ be.A. might B.mustnt C.cant D.must6、The man in the office_be Mr. Black, because he went home just now.A.mustnt B.may not C.cant D.neednt7、Can you go surfing with us this afternoon? Id like to , but I _ look after my sister at home , because my mother is ill.A.need B.must C.have to D.should8、May I take this book out of the reading room? _. Please read it here.A. Certainly B.No, you neednt C.No, you mustnt D.No, you may not【情态动词活学巧练】11 John_ come to see us tonight, but he isnt very sure yet. A. may B. canC. has to D. must2 They _ do well in the exam. A. can be able to B. be able toC. can able to D. are able to3 May I take this book out? No, you_. A. cant B. may not C. neednt D. arent4 You_ go and see a doctor at once because youre got a fever.A. can B. must C. dare D. would5 Can you speak Japanese? No, I_. A. mustnt B. cant C. neednt D. may not21 He_ be in the classroom, I think. No, he _ be in the classroom. I saw him go home a minute ago. A. can; may not B. must; may not C. may; cant D. may; mustnt2 Shall I get one more cake for you, Dad? Thanks, but you_, Ive had enough.A. may not B. must not C. cant D. neednt3 Even the top students in our class cant work out this problem, so it be very difficult.A. may B. must C. can D. need4 He isnt at school. I think he _ be ill. A. can B. shall C.