第004章助动词和情态动词.doc

第四章助动词和情态动词
助动词和情态动词都是动词的不同形式，不能单独使用，通常和谓语中心词一起构成谓语动词的各种时态，语态及其他用法。
第一节助动词
一、助动词的种类
英语中的助动词有四种：
（1）be(is, am, are, was, were, being, been )
（2）have(has, had, having)
（3）do(does, did)
（4）shall, will(should, would)
二、助动词的用法
助动词本身没有独立的词义，不能单独构成谓语，通常和谓语动词连用表示时态、语态、语气或构成否定句和疑问句。
1、构成除一般现在时和一般过去时之外的各种时态。例如：
she is having a meeting.她在开会。
I shall help you any minute.我将随时帮助你。
I have been working in the company for years.我已在这个公司工作多年了。
They’ll discuss the problem tomorrow.他们明天将讨论这个问题。
Soon they would have reached their time limit and must return to the camp.
不久规定的时间就要到了，他们就得回到营地。
He has written the paper.他的论文已经写完了。
They had finished the work before I arrived there.在我到那之前，他们已经把工作做完了。
2、构成被动语态。助动词和过去分词连用可构成被动结构。例如：
The documents have not been signed by the manager.这些文件经理还没签字。
The machine was made in Japan.那部机器是日本造的。
Smith has been sent to California for a year.史密斯被派到加利福尼亚去一年。
3、构成否定句和疑问句
Do you often go to the library?你经常去图书馆吗？
Did everything come off all right?一切进行得还顺利吗？
I don’t like the film.我不喜欢这部电影。
He didn’t answer the question the teacher asked.他没有回答老师问的问题。
4、加强语气。助动词可放在实义动词前以加强语气。例如：
I do feel that way.我的确有那种感觉。
They think I didn’t read the passages, but I did read.
他们认为我没有看那些文章。但我确实看了。
The letter we were expecting never did arrive.我们期待的信一直没有到。
5、用于替代，以避免重复。例如：
He can cook as well as she does (as well as she cooks) 他的烹调技术和她的一样好
I thought she’d come, but she didn’t (=but she didn’t come)我原以为她会来，但她没来。
Do you mind if I open the window? No, please do(open the window).
6、由had, should, would等构成各种虚拟语气。例如：
If I had enough time now, I would help you.假如我现在有时间，我就去帮助你。
If they had accepted the advice, they would have succeeded.
如果他们接受了那个建议，他们也许就成功了。
第二节情态动词
情态动词具有一定的词义，没有人称和数的变化，不能单独构成谓语，和谓语动词连用表示委婉语气或表示愿望、态度或推测等意义。
一、 情态动词的种类
英语的情态动词有下列几种：
二、 can和could的形式和用法
1、表示能力。表示天生或学到的能力，can表示现在的能力，could表示过去的能力。例如：
I can read French and German but I can’t speak either of them. I can only speak English.
法文和德文我都看得懂，但不会说，我只会说英语。
She can drive, but she can’t ride a bike.
她会开车，但她不会骑自行车。
The lecture couldn’t be understood by anyone present.
此次讲演未能被在场的任何人理解。
My son could read and write when he was four.
我的儿子在四岁时就能读会写。
2、表示许可。can 或could 与实义动词连用可表示许可。例如：
Students can’t smoke in the classroom.学生们不许在教室抽烟。
I can see him tomorrow.我明天可以见到他。
I could borrow my father’s car whenever I liked.我什么时候想借，就可以借我父亲的汽车。
Before our town became so big, we could climb trees in the woods and fish in the river. But we can’t now.
这个小镇还没变得这么大之前，我们可以在树林里爬树，在河里钓鱼，可是现在不行了。
3、表示可能性。表示此意的表示“理论上的可能性”，如果表示的是实际上的可能性的话，则使用could或may.例如：
Even experienced teachers can make mistakes.即使经验丰富的教师也可能会犯错误。
Our club finances can be improved.
我们俱乐部的财务状况还可以进一步得到改善。（指尚有问题存在）
Our club finances may be improved.
我们俱乐部的财务状况不定可以得到改善。（已经有了改善的提案）
It could be better to stay here.
说不定待在这里比较好。
She could have gone on vacation already.
说不定她已经去度假了。
4、表示推测。can和could表示推测的这一用法通常用于否定句或疑问句中，表示对现在、将来及过去情况进行否定的推测。通常有两种形式：
1）表示对现在或未来情况进行否定的推测，其结构为：can’t (couldn’t) can’t(couldn’t)+动词原形式或can’t (couldn’t) +be+现在分词。
She couldn’t make mistakes on this matter. 在这个问题她不可能犯错误。
This story can’t be true.这个故事不可能是真的。
I think it’s right. She can’t make a mistake.我想应该没事，她不可能犯错。
2）表示对已经发生的情况进行推测，其结构为:“can’t(couldn’t)+have+过去分词。”例如：
she can’t have gone to school. We have no school today.她不可能到学校去，今天我们学校放假。
He couldn’t have said such a thing.他应该不会说出这种话的。
5.can用于固定搭配中。can可与其他词连用构成固定搭配。例如：
I can but do my best.我只好尽全力了。
I can’t help but cry.我忍不住哭了起来。
I cannot help declining his offer.我不得不委婉拒他的提议。
You cannot be too careful when crossing the street.穿越马路时怎么小心也不过分。
三、can(could)与be able to 的区别
1、在表示能力时can和be able to 可以互换使用。例如：
I can (am able to) speak French.我能说法语。
She could (was able to ) read novels when she was four years old.
她4岁时就能看小说了。
2、在表示已经“设法或成功做了某事”时，用不能用例如：
he’d not like to go with me at first, but I was able to persuade him
起初他不愿和我一起去，但是我终于说服了他。
He was able to pass his examination as a result of his hard study.
由于他的努力学习，考试终于及格了。
四、may和might的形式和用法
1、表示可能性、推测。May和might在表示可能性、推测时。意为“也许，可能，大概”。通常有于肯定句中。具体有两种用法。
（1）表示对现在或未来情况进行推测，其结构为“may(might)动词原形或+be+现在分词。”例如:
Such an experienced teacher may sometimes make mistakes.
经验这么丰富的老师有时也可能会出差错。
It may snow tomorrow.明天很可能下雪。
They are ready for a strong earthquake which might occur.
他们对可能发生的大地震已经有所准备。
I think it might rain.我想可能要下雨。
He may be having the meeting now.也许他现在正在开会。
（2）表示对已经发生的情况进行推测，其结构为：“may(might)+have+过去分词”例如：
I thought my uncle might have missed the train.我想我的叔叔可能错过了火车。
They might have known the matter earlier.他们可能早知道那件事了。
注：may有时也可用于否定句中，这时not不是否定may的，而是否定句子里的动词。
She may not know the truth.她可能不知道那件事。
She may not have known about the matter.她可能还不知道那件事。
2、表示许可。
may或might可以用于陈述句或疑问句中表示许可。意为“可以¼¼，做¼¼也可”。其否定形式为，may not,也可用mustn’t。例如：
You may use my dictionary.你可以用我的词典.
May I borrow your bike? No, you may not我可以借你的自行车吗？不可以。
My boos told me I might have a vacation.老板告诉我说我可以休假。
3、might 表示责备，不满。此种用法中含有条件从句内容的委婉说法，可以说是省略了表示假设或虚拟的从句或短语。例如：
You might hear a pin fall.连针落地的声音都清晰可闻。
I might have known you would have come back so late.我若知道你那么晚回来就好了。
You might have told the truth.你本来可以讲实话的。
4、用于固定搭配中。例如：
you may (just) as well know the truth.你知道真实情形地无妨。
I might (just) as well stay at home tonight.我今晚还是待在家里吧。
It may well rain.或许会下雨。
You may well say so.你大可那样说
5、用于表示目的状语从句中。例如：
They moved over a little so that I might sit down.他们靠过去一点，我便可以坐下来。
Mr. Smith speaks English slowly in order that his students may follow him
史密斯英语说得很慢，好让学生能听懂。
6、用于让步状语从句中。在让步状语从句中，通常不用将来式，从句中常用一般式或情态动词may或might.例如：
Whatever he might say, no one believed him.不管他说什么，都没有人相信他。
However hard you (may) try, you will never be able to participate in the Olympic Games.
不管你多努力，你都无法参加奥林匹克运动会。
7、may表示祝愿。may通常用倒装结构，表示祝愿。例如：
May success attend you!祝你成功！
May you have merry Christmas!祝你圣诞节快乐！
五、must的形式和用法
1、表示义务。通常用于肯定句、疑问句，表示义务，必要性。例如：
You must start at 6 tonight.你今晚六点钟必须动身。
You must talk to your daughter about future.你必须跟你的女儿谈谈她的前途。
“Must I wash the dishes at once?” ”Yes , you must.(not, you needn’t)”
“我必须马上洗盘子吗？”“对，必须马上洗。（不，不必马上洗。）”
2、表示不允许。通常用于否定句，表示禁止。例如：
You must not speak ill of others.你不可以说别人坏话。
She must not leave her room.她不允许离开她的房间。
3、表示推测
用于肯定句中表示对现在、将来或过去情况的推测，通常有两种形式：
（1）表示对现在或未来情况进行肯定的推测，其结构为：“must+动词原形或must + be+现在分词”例如：
It must rain soon.不久一定会下雨。
He must be having the meeting now.他现在一定是在开会。
She must dislike such a man.她可能不喜欢这种男人。
（2）表示对已经发生的情况进行肯定的推测，其结构为“must + have+过去分词”。例如：
It must have rained last night, for the ground is wet.昨晚一定下雨了，因为地上湿乎乎的。
No one answers the phone bell. They must have already gone out.电话没人接，他们一定出来了。
六、must和have to 的区别
1、含义不同。
must和have to作情态动词用时，意思很接近，但含义有所不同。Must表示“必须”，通常着重于说话者的主观看法，认为有义务、有必要去做某事。Have to着重于表示客观的需要，含有“不得不”的意思。例如：
you must be back by 3 p.m.你必须三点以前回来。（表示命令）
you have to be back by 3.p.m.（客观需要）
2、形式不同。
从形式上看must只有一种形式，可用于现在时、过去式（多用于间接引语中）。而have to却有4种形式，即have to, had to , will/shall have to , would/should have to , 可用于现在时、过去时、将来时和过去将来时。例如：
He said he would have to (must) get his entry visa for Japan.
他说他得办理去日本的入境签证。
She had to return before Sundays.她得在周日以前回来。
I haven’t any money with me, so I’ll have to borrow some from my friends.
我没钱了，只好向朋友借一点。
七、need和dare的形式和用法
这两个词作情态动词时，无人称变化，只用于否定句、疑问句和条件句。
1、need表示“愿意”；dare表示“敢于”例如：
You needn’t work so hard.你不必工作得这么辛苦。
Mary dare not touch the snake.玛丽不敢碰那条蛇。
You need not meet him unless you’d like to .你不必要见他，除非你愿意。
I don’t know whether he dare try.我不知道他是否敢试试。
2、need 可用于完成式，其形式为：“needn’t + have+过去分词”表示“过去做了某事，但事实上没有必要做”。例如：
I need not have got up so early.我本来没必要那么早起床的。（但事实上已早起床）
You needn’t have bought the dress.你没必要买那件衣服。（但你却买了）
3、need的肯定式为must, 否定式为needn’t，例如：
He needn’t see him, but I must.如果他不想去，就别去了。
You needn’t see him, but I must.你没必要去见他，但我得去。
4、 need和dare也可用作实义动词，作实义动词时，要注意人称和时态的变化，后面可以跟不定式等各种结构。例如：
A fence needs the support of the tree stakes, doesn’t it?一个篱笆要有三个桩，不是吗？
I have never dared to tell him about it.我一直不敢把这事告诉他。
You don’t need to come if you feel sick.如果你不舒服就不要来。
5、dare作实义动词时，其疑问句或否定句后面的不定式符号常省略。例如：
Does the litter girl dare(to) enter the house in the darkness?
那个小女孩敢进那个漆黑的房子吗？
He didn’t dare (to) disobey.他不敢不服从。
八、Will和would的形式和用法
１、Will或would可用来表示主语的强烈意志或主张，意为“无论如何总要¼¼”will表示主语现在或经常性的情况，would表示主语过去的情况。例如：
My children will not listen to me我的孩子总是不听我的话。
I will marry you whatever happens.无论发生什么事，我都要和你结婚。
His father was angry because he wouldn’t obey him.他不听话，他父亲很生气。
That windows wouldn’t open.那扇窗户打不开。
That manager would have his own way.那位经理总是一意孤行。
2、will作情态动词用时，表示将来的意志、意愿。例如：
I’ll send photos to you soon.我很快就会把照片寄给你。
I shall be glad if you will help me.如果你愿意帮助我，我会很高兴。
I will never talk about it again.我永远不会再提这件事了。
3、will表示命令、请求、规劝等。
Will you pass me the salt, please?请你把盐递给我。（表示请求）
Go and get the newspaper, will you?去把报纸拿给我。（表示命令）
Won’t you sit down.请坐吧！（表示规劝）
You will forgive me, won’t you?你会原谅我，不是吗？（表示请求）
４、would表示过去的习惯、习性、倾向等。例如：
when I was a child, I would go skiing.我小时候经常去滑雪。
We would stay up all night talking about our future.（那时候）我们经常彻夜谈论我们的将来。
九、used to和would的用法比较
use to和would都可以表示过去时间经常的习惯动作，但它们的含义和用法不尽相同。
１、would是以一种回忆往事的心情来描述过去经常重复的习惯动作，而used to则强调过去与现在的对比，并且表示较远、目前不复存在的习惯。例如：
Every evening she would teach us to read and write.那时她每天晚上都教我们学文化。
My brother used to be a worker, but now he is a college teacher.
我哥哥过去是工人，但现在却是一位大学老师。
He will not have the money to spend on books as he used to .他无法像以前那样有钱买书了。
2、would只能和表示动作的动词连用，而used to既能和动作动词连用，也能和状语动词连用。例如：
There used to be a temple there.以前那里曾有座古庙。（不能用would）
He would spend all he earned on books.他总是把挣来的每分钱都花在买书上。
十、shall的形式和用法
1、shall可用在主语是第一人称或第三人称的疑问句中，表示说话人征求对方的允诺。例如：
Shall I fetch a doctor for you?我去为你请医生来好吗？
Shall he come at once?要他马上来吗？
“Shall we go to the concert tonight?”“Yes, let’s (not let’s not).”
“今晚我们去听音乐会好吗？”“好，我们不要去。”
２、用在主语是第二、第三人称的陈述句中，表示说话人给对方的义务、命令、许诺等。例如：
You shall do as you see me do.你照我的样子办（义务）
You shall leave here at once.你必须马上离开这儿。（命令）
He shall be paid.他会得到报酬的。（许诺）
They shall never interfere in my private affairs again.他们决不可以再干涉我的私事。
十一、should和ought to 的形式和用法
１、 should和ought to 后接动词原形，表示义务。例如：
You should do what your parents tell you.你应该照你父亲说的去做。
You don’t look well. You ought to go to see the doctor.你气色不太好，应该去看医生。
You should apologize to him.你应该向他道歉。
He ought not/oughtn’t to him他不应该喝太多的酒。
２、 should和ought to后接现在完成时，表示应该做而没有做的事，表示责备、后悔等。
例如：
I should have been kinder to him当时我要是对他再亲切一点就好了。
He shouldn’t have said such a thing.当时他不该说那种话。
He ought to have worked harder.他应该更努力读书的。
You ought not to have been so stupid.你当时不该那么笨。
Exercise 4
1、选择题
1.Mary 　　　　　my letter; otherwise she would have replied before now.
A. has received B. ought to have received
C. couldn’t have received D. should have received
2. Mary didn’t go to the party last night because she the baby for her sister until 9:30.
A. must have looked after B. had to look after C. must look after D. has to look after
3.From the tears in her eyes we can deduce that something sad
A. must have occurred B. would have occurred
C. might be occurring D. should occur
4.As it turned out to be a small house party, we so formally.
A. needn’t dressed B. didn’t need have dressed
C. did not need dress up D. needn’t have dressed up
5.Henry’s car stopped on the highway. It out of gas.
A. may not run B. may have run C. muse run D. ought to run
6.You pay the money, but you do so at once.
A. needn’t¼¼and B. need¼¼need C. must¼¼must D. must¼¼needn’t
7.The car plunged into the river, the driver get out but the passengers were drowned.
A. was able to B. succeeded to C. could D. might
8. if you me, I shall be very grateful to you.
A. helped B. will help C. are helping D. will be helping
9. I in the kitchen when you phoned.
A. must have been B. must be C. can be D. could have been
10. I can’t find Mr. Fox in her office, she for home.
A. might have started B. might start C. may be starting D. may start
11. you don’t need for his permission every time you want to leave the room.
A. to ask B. ask C. asking D. being asked
12. They have gone out because the light’s on.
A. mustn’t B. can’t C. may not D. isn’t able to
13. Surely nothing be going on there so late at night.
A. needn’t B. shall C. could D. ought to
14. If you can eat all these apples you have a good digestion.
A. must B. can C. may D. might
15.I wonder why they haven’t arrived yet. I told them how to get here but perhaps I them a map.
A. should give B. had to give C. must have given D. ought to have given
16. “Must I come at four o’clock?”“oh, no, you come at four.”
A. mustn’t B. needn’t C. shouldn’t D. couldn’t
17. We had plenty of bread, so I a loaf.
A. needed not to buy B. need not to have bought
C. needn’t have bought D. didn’t need to buy
18. you that if you don’t want to.
A. don’t need to do B. needn’t to do C. need to have done D. don’t need to
19. The students in the classroom not to make such a big fuss.
A. must B. need C. ought D. dare
20. An ambulance was waiting in the street. Somebody hurt or killed.
A. should have been B. should be C. must have been D. should have not been
21. I didn’t enjoy the concert yesterday; it was a confusion, and the band didn’t play as it
A. did B. has done C. used to D. have done
22. Oil and other chemicals kill fish and make water bad for drinking.
A. would B. must C. can D. should
23. When we arrived at the pier, the ferry had still not arrived; so we .
A. needed not B. needn’t have hurried
C. didn’t need to hurry D. need not to have hurried
24. The line is busy; someone the telephone now.
A. should be using B. must have been using C. uses D. must be using
25. you quit your job until you find another one.
A. had better don’t B. had better not C. had better not to D. would better
26. He hardly say anything more since we know all about it.
A. needs B. need C. need to D. needn’t
27. “That must be a mistake.”“No, it a mistake”.
A. must not be B. needn’t be C. can’t be D. would not be
28.The swimmer was very tired but he reach the shore before he collapsed.
A. might B. could C. succeeded D. was able to
29. Dr. Jones, many students want to see you. they wait here or outside?
A. Do B. Will C. Shall D. Would
30.Professor Wang be in Beijing because I saw him in the library only a few minutes ago.
A. must not be B. can’t C. may