专题七 情态动词、系动词

　　在英语中，表示主语动作或状态的词就叫做动词。根据动词的意义及在句子中的作用，可将动词分为实义动词(v)、系动词(link-v)、情态动词(modal verb)和助动词(v. aux)四种类型。

　　下面我们就来看看情态动词和系动词的具体用法。

　　一、情态动词

　　情态动词本身有一定的意义，但不能独立作谓语，要和动词原形一起构成谓语，表说话人的语气和态度。它没有人称和数的变化。常见的情态动词有：

　　1. can表示能力，有“能”“会”的意思;表示可能性，多用在否定或疑问句中;表示请求和许可。

　　如：The parrot can speak three languages. 这只鹦鹉能讲三种语言。

　　Can I borrow the book from the library?我可以从图书棺借这本书吗?

　　Shanghai can be very cold in March. 上海三月份可能会很冷。

　　拓展延伸can还有过去式could 可表“能，会”，又可以和be able to替换，而be able to有 更多时态。 如：

　　He could swim when he was four. =He was able to swim when he was four. 他四岁时就会游泳。 在一般疑问句中，can/could 常用来表示请求或征求对方意见，用could 比用can语气更加委婉和客气。类似用法的还有Will /Would you (please)…等句型。

　　如：Could you tell me how I can get to the post office? 你能告诉我怎样到邮局吗? Would you please turn up the radio?请你把收音机开大点，好吗?

　　2.may表示“许可”时，相当于can，其否定回答用can’t/mustn’t;表推测时，常用在肯定句中，表“可能”。

　　如：-May I borrow your ruler?我可以借用您的直尺吗?

　　-No, you can't /mustn't. 不行。

　　She may be a teacher. 她可能是一名教师。

　　拓展延伸may可表示祝愿。如： May you succeed! 祝你成功!

　　3.must表示“必须;必要”，以“must”开头的一般疑问句其肯定回答用“must”，否定回答用“needn't”或“don't have to”。 must表推测时，常用在肯定句中，是“一定”的意思，其否定形式mustn ' t表“禁止”的意思。

　　如：-Must I leave now?现在我必须离开吗?

　　-No，you needn't /you don't have to. 没有必要。

　　This book must be Lucy's . Look! Her name is on the book cover. 这本书是露西的。看!封面上还有她的名字。

　　You mustn't draw on the wall. 你不准在墙上画画。

　　拓展延伸must表示说话人的主观看法，只有一般现在时;have to强调客观要求，有时态、人称和数的变化。如： My mother is ill. I have to look after her now. 妈妈病了，我得去照看她。

　　4.need作情态动词时，常用在否定和疑问句中，表示“需要;要”的意思。

　　如：Need we finish the work now?现在我们需要完成这项工作吗?

　　They needn ' t look after him. 他们不需要照顾他了。

　　拓展延伸need还可以用作行为动词，可以用于各种句型。如：

　　Does he need any help? 他需要帮助吗?

　　The desk needs repairing. 这张桌子需要修理。

　　5.shall 用于第一人称，表示说话人征求对方意见，过去式为should;will 用手第二人称的疑问句中，表示说话人向对方提出请求和建议，过去式为would。

　　如：Shall I go shopping with you?'我可以同你去购物吗?

　　I don't know what I should do next. 我不知道下一步该干什么。

　　Would you please come a little earlier?请你来早一点好吗?

　　6.情态动词had better的用法

　　(1)had better 后接动词原形，表劝告、建议，意为“最好”。“You'd better… ”含有强制命令的语气，对长辈不宜使用。

　　如：You'd better ask that policeman over there. 你最好问一下那边的那个警察。

　　(2)慎用had better! 注意以下四条：

　　①had better表达的是说话者强硬性的建议，告诫别人(包括自己)如何做。 如：Granny, the hospital is not very near. We'd better catch a bus. 奶奶，医院不是很近。我们最好坐公共汽车。

　　②had better不用于礼貌的请求或征询，它隐含一种警告或威胁。 如：You ' d better finish the work today and bring it tomorrow. 你最好今天就把作业完成，明天带来。

　　③had better意思接近should，但它除了表示语气强硬以外，还表示马上要去做的事情，比should更紧迫。 如：You’d better see a doctor at once. 你最好马上去看医生。

　　④had better不含比较的意思，该结构表示“It would be good to… ”，而不是“It would be better to…”。

　　二、系动词

　　系动词有实际意义，但不能单独做谓语，必须与表语一起构成句子的谓语，说明主语的性质、状态或身份等。 它分为完全系动词和不完全系动词。

　　1.完全系动词(be)可接名词、代词、形容词、副词、介词短语、非谓语动词短语、句子做表语。如： I'm a student. 我是个学生。(名词) He is fine. 他很好。(形容词) It is me. 是我。(代词) Are you there?你在那儿吗?(副词) She is at school. 她在学校读书。(介词短语) He is to come soon. 他过会儿该来了。(不定式) My job is teaching English. 我的工作是教英语。(动词的ing形式) My idea is that we will start now. 我的想法是我们现在就开始。(句子)

　　2.不完全系动词 (get，turn，feel，smell，look，sound，taste)一般只接形容词做表语。如：When spring comes, it gets warmer and warmer.

　　春天来了，天气变得越来越暖和了。 Food may go bad soon if it is not put into a fridge.

　　食物如果不放进冰箱里就会很快变坏。 My brother became / turned a teacher after his graduation.

　　我哥哥毕业后就当上了老师。(注意become和turn的用法区别)

　　实战演练(2×50) 计分:

　　1. --Mary, ____ you speak Chinese? -- Yes, but only a little.

　　A. will B. can C. could

　　2. --Must I do the work now? -- No, you ____. You can do it later.

　　A. can't B. mustn't C. needn’t

　　3. -- I can't stop smoking, doctor. -- For your health, I'm afraid you ____.

　　A. can B. need C. must

　　4. -- Whose book is it? -- It ____ be Bob's sister's. She is only a baby.

　　A. must B. mustn't C. can't

　　5. -- Jill looks so painful, there ____ be something wrong with her.

　　-- Oh, dear! We'd better take her to the hospital at once.

　　A. can B. should C. must

　　6. --Is Simon coming by train? -- He should, but he ____ not. He likes driving his car.

　　A. may B. need C. must

　　7. -- May I try on the jeans? -- Yes, you ___.

　　A. should B. can C. must

　　8. -- Do you know any traffic rules?

　　-- A little. When the traffic lights are red, we ____ stop and wait.

　　A. may B. can C. must

　　9. I think schools ____ allow students at least one hour a day for sports.

　　A. would B. should C. could

　　10. -- Can I swim in the lake. Dad?

　　-- No, you ____. Haven't you seen the notice “No Swimming”?

　　A. may not B. mightn't C. mustn't

　　11. -- Are you going to Beijing by air?

　　-- It's fast but a little expensive. So I am not sure. I __ take it.

　　A. will B. may C. must

　　12. -- Could I borrow your dictionary? -- Of course you ____.

　　A. can B. will C. should

　　13. --Don't forget to come to my birthday party tomorrow. --No,____.

　　A. I don't B. I won't C. I can't

　　14. -- Will you please stay here for the party?

　　-- Sorry, I ____. I'll have to go to an important meeting.

　　A. mustn't B. needn't C. can't

　　15. -- Must I tidy the room now?

　　-- No, you ____. You can do it after breakfast.

　　A. mustn’t B. need C. don't have to

　　16. -- You must come back every month. -- Yes, I ____.

　　A. will B. must C. should

　　17. -- Is this coat Jane's? -- It ____ be hers, but I'm not sure.

　　A. will B. may C. must

　　18. -- ____ we go and fly kites today? -- That's a good idea.

　　A. Should B. Must C. Shall

　　19. --ls your brother playing computer games, Ted?

　　-- He ___ do that because the computer doesn't work.

　　A. may not B. can't C. mustn't

　　20. -- I don't mind telling you what I have known.

　　-- You ___, and I am not asking you for it.

　　A. needn't B. mustn't C. may not

　　21. _____ you help me?

　　A.Will B.Shall C.Must

　　22. You ______watch TV if you’ve finished your homework.

　　A. can B. must C. need

　　23. I have seen lights in that empty house. Do you think I _____report it to the police?

　　A. should B. may C. will

　　24. -- Who is the girl standing over there?

　　-- Well, if you ______know, her name is Mary.

　　A. may B. can C. must

　　25. -- Excuse me, could you tell me where the supermarket is?

　　-- It’s two blocks straight ahead. You _____miss it.

　　A. mustn’t B. can’t C. shouldn’t

　　26. -- Mom, there goes the bell.

　　-- Oh, it _____ Annie. I invited her to come for dinner.

　　A. can’t be B. must be C. may be

　　27. I’ll let you see the patient in an hour if you _____wait here.

　　A. will B. must C. can

　　28. Whoever can answer one of my questions ______get a prize.

　　A. would B. should C. will

　　29. Tom, you ______leave all your clothes on the floor like this.

　　A. wouldn’t B. mustn’t C. needn’t

　　30. It’s 7:50. You ____hurry, or you’ll be late.

　　A. might B. will C. had better

　　31. In spring, all the flowers in the garden _______ sweet.

　　A. taste B. smell C. become

　　32. She _______ like her mother in character.

　　A. is B. seems C. looks

　　33. In late autumn leaves _______ brown.

　　A. get B. turn C. come

　　34. Look! There _______ so many people here on vacation.

　　A. have B. are C. be

　　35. His classmate_______ a singer.

　　A. were B. grew C. has become

　　36. My job is ______ you math.

　　A. to teach B. teaches C. taught

　　37. How time flies! Three years _______ really a short time.

　　A. are B. is C. was

　　38. It sounds _______ a good idea.

　　A. as B. is C. like

　　39. Her temperature _______ to be all right.

　　A. seems B. sounds C. looks

　　40. His wish to become a driver has _______ true.

　　A. turned B. come C. been

　　41. Little Jim’s speech sounds _______.

　　A. friendly B. wonderfully C. nicely

　　42. When her mother came home yesterday, it was _______ dark.

　　A. going B. running C. getting

　　43. These apples taste _______.

　　A. to be good B. good C. well

　　44. -- How about the cloth you bought yesterday?

　　-- That’s very beautiful. It _______ so soft.

　　A. felt B. feels C. is feeling

　　45. When his brother telephoned him last night, he _______ asleep.

　　A. felt B. fell C. fall

　　46. The food will _______ bad easily in such hot weather.

　　A. go B. went C. turn

　　47. It _______ that he was late for the train.

　　A. looks B. says C.seems

　　48. What does your brother look _______?

　　A. like B. as C. after

　　49. The girl’s voice is so sweet and her songs _______ very beautiful.

　　A. taste B. look C. sound

　　50. What a lovely day! I hope it _______ fine.

　　A. stayed B. will stay C. will get

　　参考答案

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