助动词(2)

第17讲 助动词 （一）

概述

英语动词，按其在构成动词词组所起的作用，分为主动词和助动词两大类。助动词又分为基本助动词、情态助动词和半助动词。

英语情态助动词共有14个： 现在时形式 过去时形式 can could may might will would shall should must --- need --- dare Dared --- ought to --- used to

17.1 情态意义表示法 1、表“能力”和“可能”

A. 表示“能力”（ability）,可用can, could, be able to. Can 既能表示现在的能力，也能表示将来的能力。 Look！ I can do it!

I can’t do it now, but I can do it later.

Can既可指具体做某件事的能力，也可泛指一般的能力。 I can climb this cliff. He can drive a car.

表“能力”，can和be able to 很多情况下可以交替使用。 As I have got enough money, I can/ am able to help her. 指将来的能力，更常用will/shall be able to I’ll be able to speak German in another two months. 表示过去的能力，可用could和was/were able to

在肯定句中，表示泛指能力用could，表示具体能力用was/were able to

She could play the piano when she was only six. He was able to translate the article without a dictionary. 但在否定句中，两者无此限制。

I couldn’t/ wasn’t able to play the piano when I was at school.

B. 表示“可能”（possibility）,可用may, might, can, could. may/ might 表示“可能”，往往可以交替使用，无时间上的差异，might比较婉转。may / might 既可以表示现在的可能，

也可表将来的可能。 It may/ might be true.

He may/ might be still waiting at the door. 在疑问句中表“可能’,须用can而不用may. Where can he be?

表示“不可能”，通常用can’t. She can’t love him.

用can表示可能，较多的用于否定句和疑问句，而could不受此限制。

It can’t/ couldn’t be true.

If you don’t have a guide, you could lose your way.

表示过去的可能，可用may/might +不定式完成体或不定式完成进行体。

He may/ might have been hurt. You might have killed yourself.

也可以用can/could+不定式完成体表示可能。 He can’t/could have been hurt.

用might/ could +不定式完成体有时可以表示本来可以做却没有做。

You might have finished the work last week. I could have passed the examination, but I failed.

2、表示“许可”和“不许”。

A. 请求对方许可（permission）可用can, could, may, might. May/can 与might / could 相比，后者较为婉转，更有礼貌。在口语中常用can表许可。 Can/could/may/might I smoke here?

表示“给予许可”，常用May/can，不用might / could。 Could I use your phone? Yes, of course you can.

B. 表示不许可用may not 或者cannot Can I go out for a moment? No, you can’t.

May I use your car for a few days? No, you may not.

注意may not 表示“不许可”的过去形式并不是might not. He may not go. (I don’t permit him to go) He might not go.(possibly he will not go.) 若要表示过去不“许可”，通常可以说： He was not allowed to go. I didn’t permit him to go.

3、表示“义务”和“必然”。

A. 所谓表示义务（obligation），即表示必须、应该做某事。

表示这些意义，可用should, ought to, must. 用这三个情态助动词表示义务，其口气强弱略有差别。

用should/ought to 表示应该，带有劝说之意，两者可以交替使用。

We should learn from the model workers You should/ought to drink less.

Should / ought to +不定式完成体，表示本应该做却没做，或本不应该做却做了。

You should /ought to have asked my permission first.

You shouldn’t/ oughtn’t to have been resting at that time of day.

Must（必须）表示敦促或者命令，表示将来或者过去的必须，使用have to的相关形式。 You must be back by ten o’clock. We’ll have to do it again. I had to leave at six yesterday.

Must的否定形式有两种。一种是must not, mustn’t，表示禁止；第二种是need not, needn’t，表示不必。 You mustn’t talk like that. You needn’t do it once.

Needn’t相当的形式有：don’t need to/ don’t have to/ haven’t got

to.

You don’t need to do it once. You don’t have to do it once. You haven’t got to do it once.

过去形式通常用 didn’t need to, didn’t have to You didn’t have to do it once.

表示必须，must 与have to 的意义接近，但must更侧重表主观，have to 表客观。

He must move the furniture himself.

B. 所谓表示必然（necessity）就是根据说话人的判断和推测认为必然会有某种情况。表示这种意义，可用should, ought to 和must,其中以用must口气最为肯定。 She should be here in a minute.

These young trees ought to provide shade in ten years. Careless reading must give poor results. 表示否定的推测，则需要使用can’t You can’t have any difficulty getting the tickets. 如果表示过去的推测，用must/ can’t +不定式完成体 Her eyes are red. She must have been crying.

He can’t have been to your home. He doesn’t know your

address.

4、表“预见”与“推测”

A. 表示预见（prediction）,即表示单纯将来，可用will/ shall+不定式。除英格兰以外的说英语国家如美国、新西兰、南非的标准英语中，shall 已完全为will 所取代，这就是说，will可用于一切人称表示将来。

B. 表示推测（predictability）,除用should, ought to 和must外，还可用will/ would.

Will表示推测，口气低于must, would次之 They should/ ought to be home by now. They would be home by now. They will be home by now. They must be home by now.

5、表示“意图”、“意愿”和“决心”。

A. 表示意愿（willingness）,即愿意做某事，可用will, would, shall. 用will 表示意愿，可用于一切人称的主语. I will lend you the money if you need it. Will you sing at the party tomorrow evening? Will you please open the door for me? Would you lend me your pen a minute?

Certainly, I will.【表示接受请求时，用will】 表示不愿意，可以用will not/ won’t I will not do anything for you.

用shall表意图，一般适用于第二、第三人称。 You shall stay with us as long as you like.(说话人意愿) Shall you take a holiday this summer? （听话人意愿） B. 表示意图（intention）,即打算做某事，也可用will, would, shall. Will可用于所有人称，表示过去的意图可用would. I will write to her tomorrow. Why will you go there?

He would see her the next day, so he didn’t write to her. 用shall表“意图”，常用语第二、三人称，表示说话人意图。在疑问句中，表示征询听话人得意图。

You shall get a promotion. ( I’ll give you a promotion.) Shall I carry the suitcase for you?

C.表示决心（determination）,既坚持要做某事，也可用will, would, shall，均需重读，且不能缩写。Will表示“决心”，“坚持”，表过去的决心，可用would.

I will take the job and no one is going to stop me. If you will go, you may go at once.

She would marry him in spite of my warning that is was unwise.

Shall表决心，主要用语第二、三人称 You shall obey my orders. He shall leave the country at once.

Shall 这种用法的否定形式，表示说话人禁止，威胁。 Foreign countries shall not interfere in our internal affairs.

6、其他情态意义。

A. should 可在某些语境中表示惋惜、忧虑、欢欣、惊讶等感情色彩。

They were amazed that she should have done so much in so short a time.

在某些惯用的疑问句中 How should I know?

在某些虚拟句式中使用，并不表示情态意义。 I insisted that he go/ should go with me.

B. would 可用于委婉的陈述, 请求等 I don’t think he would be so careless. Would you like to stay here tonight?

C. 作为情态助动词表示胆敢，dare通常只用于否定陈述句和疑问句。

I dare not go there.

How dare he say such rude things about me?

Dare 还可用作主动词，也通常用于否定和疑问句，带或不带to均可。

She didn’t dare (to) say anything about it.

D. need即可作情态动词，也可做主动词，表示“必须”、“需要”。作为情态动词，need 只用语否定句和疑问句。 He needn’t worry about it. Need I collect the parcel myself?

作情态助动词提问，其答语如果思肯定的，须用must;如果答语是否定的，则用needn’t .

“needn’t+不定式完成体“表示本不必做却做了，和didn’t need to 是有区别的。

You needn’t have bought that house. I didn’t need to go to the station. I needn’t have gone to the station.

E. used to (只有过去时形式，没有现在时形式)表示过去习惯动作或状态，这种情况现已不复存在。

There used to be an old temple at the corner of the street, but it was destroyed in the war and has never been rebuilt.

He used to live in Shanghai, but he has long given up smoking. Used to的否定形式，可以用usedn’t, didn’t use to. He didn’t use to smoke cigarettes. He usedn’t to smoke cigarettes.

17.2 情态动词的推测性和非推测性 （略）

Lecture 18 助动词（二）

本讲将介绍的是半助动词(Semi-auxiliary)以及助动词(Auxiliary）的缩略形式(Contracted Form)。 18.1 半助动词

半助动词指在功能上介乎主动词和助动词之间、本身带有词义的一类结构。下面就半助动词的类型以及半助动词与it...that结构的转换关系作一些介绍。 1）半助动词的类型(1) 从形态上看，可以分成三类： ?以be为其中心成分； ?以have为中心成分； ?以seem等为其中心成分。

从能否与it...that结构进行转换上看又可以分为能与不能两类 (p210-211 表格） 具体举例 （P211）

由上述诸例可知，半助动词后的主动词无一例外地用不带to不定式，这种不定式可以是一般式，也可以是进行体或完成体形式。现就以be supposed to （作“应该”解）为例来说明。 ?Why are you driving so fast in this area? You are supposed to know the speed limit .

?Mother is still not quite well. She is not supposed to be working so hard.

?Why haven't you finished your paper yet? You are supposed to have finished it by tomorrow. 2)半助动词与“it...that”结构(1)

前述带有第一类半助动词作为限定动词词组一部分的句子不能与it...that 结构相互转换。

例如可以说The boy tended to be late.但不能说It tended that the boy was late.

而带有第二类半助动词作为限定动词词组一部分的句子则能与it...that 结构相互转换.

例如可以说The boy seemed to be late.也可以说It seemed that the boy was late

为了便于说明，不妨把it...that结构称为句型I,而把“半助动词+不定式”结构称为句型II.例如： It appears that he has many friends. [I] He appears to have many friends. [II]

句型II中的不定式是采取一般形式、进行体形式还是完成体形式，是采取主动态还是被动态，取决于句型I中that-分句的限定动词词组形式。 具体例子： (P212)

18.2 助动词的缩略形式 (略)

第十七讲 情态动词【传统分类】

一、情态动词的基本用法 1. can (could)

1）表示能力，could主要指过去时间。

Two eyes can see more than one. 两只眼比一只眼看得清。 Could the girl read before she went to school? 这女孩上学前能识字吗？

2）表示可能（理论上或是逻辑判断上）。 He can’t (couldn’t) have enough money for a new car. 他不可能有足够的钱买新车。

You mustn’t smoke while you’re walking around in the wood. You could start a fire. 在林子里走时勿吸烟，那样可能会引起火灾。 3）表示允许。

Can I have a look at your new pen? 我可以看一看你的新钢笔吗？

He asked whether he could take the book out of the readingroom. 他问他可不可以把书带出阅览室。

4）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。

Where can (could) they have gone to? 他们会去哪儿了呢？ He can′t (couldn’t) be over sixty. 他不可能超过六十岁。 How can you be so careless? 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) you lend me a hand? 帮我一把好吗？

I’m afraid we couldn’t give you an answer today. 恐怕我们今天不能给你答 复。

2. may (might)

1）表允许，might可以指过去时间，也可指现在时间，语气更委婉。

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？

—

在回答以may引起的问句时，多避免用这个词，而用其它方式，如Yes, please. / Certainly. / Please don′t ./ You′d better not. / No, you mustn’t.等，以免显得太严峻或不客气。 2）表可能（事实上）。可以指过去时间，也可以指现在时间，但语气更加不肯定。

He may be at home. 他可能在家。

She may not know about it. 她可能不知道这件事。 He was afraid they might not agree with him. 他担心他们可能不同意他的意见。

They might be having a meeting, but I′m not sure. 他们有可能在开会，不过我不肯定。 3. must

1）表示义务。意为”必须”（主观意志）。

We must do everything step by step. 我们一切都必须循序渐进地做。

You mustn’t talk to her like that. 你不能那样对她说话。 --Must we hand in our exercise—books now? 我们现在就要交练习本吗？

--No, you needn’t. / No, you don’t have to. 不必。 （这种情况下，一般不用mustn’t）

2）表示揣测。意为”想必、准是、一定”等，只用于肯定

句。

He must be ill. He looks so pale. 他准是病了。他的脸色苍白。 She

s wearing a diamond necklace. She must have a lot of money. 她戴着钻石项链，一定很有钱。 4. shall

1）表征询意见，用于第一、第三人称疑问句。 Shall I get you some tea? 我给你点茶好吗？ Shall the boy wait outside? 让那男孩在外面等吗？ What shall we do this evening? 我们今晚做什么？ 2）表说话人的意愿，有”命令、允诺、警告、决心”等意思，用于第二、第三人称陈述句。 You shall do as I say. 按我说的做。（命令）

You shall have my answer tomorrow. 你明天可以得到我的答复。（允诺）

He shall be sorry for it one day, I tell you. 有一天他会后悔的，我告诉你。（警告） Nothing shall stop us from carrying out the plan. 什么也不能阻止我们执行这项计划。（决心）

′

5. will

1）表意愿，用于各种人称陈述句。

I will do anything for you. 我愿为你做任何事。 None is so blind as those who won′t see. 不愿看的人眼最瞎。

If you will read the book, I’ll lend it to you. 如果你愿意读这本书，我会把它借给你。 2）表请求，用于疑问句。

Will you close the window? It′s a bit cold. 请你把窗户关上好吗？有点冷。

Won′t you drink some more coffee? 再来一点咖啡好吗？ 3）表示某种倾向或习惯性动作。

Fish will die out of water. 鱼离开水就不能活。 The door won′t open. 这门打不开。

The boy will sit there hour after hour looking at the traffic go by.

那男孩常常坐在那里好几个钟点，看着车辆行人通过。

6. should

1）表义务。意为”应该”（某件事宜于做），用于各种人称。

You should be polite to your teachers. 你对老师应该有礼貌。

You shouldn’t waste any time. 你不应该浪费时间。 2）表推测，意为“想必一定、照说应该、估计”等。

The film should be very good as it is starring firstclass actors.

这部新电影是一流演员主演的，估计拍得很好。 They should be home by now. 照说他们现在应当已经到家了。 7. would 1）表意愿。

They would not let him in because he was poorly dressed. 他们不让他进去因为他衣着破旧。

I said I would do anything for you. 我说过我愿意为你做任何事。

2）表委婉地提出请求、建议或看法。

Would you like another glass of beer? 再来杯啤酒好吗？ Would you mind cleaning the window? 请把窗户擦一下好吗？

They wouldn′t have anything against it. 他们不会有什么反对意见。

—

3）表过去反复发生的动作或过去的一种倾向。 Every time she was in trouble, she would go to him for help. 她每遇到麻烦都会向她求助。他告诉我盒子打不开了。

8. ought to

1）表义务，意为”应该”（因责任、义务等该做），口气比should稍重。

You are his father. You ought to take care of him. 你是他父亲，应当管他。

You oughtn′t to smoke so much. 你不应该抽这么多烟。 2）表推测，暗含很大的可能，语气较弱。

Han Mei ought to know his telephone number. 韩梅该知道他的电话号码。

There′s a fine sunset; it ought to be a fine day tomorrow. 今天有晚霞，明天应该是个好天。

9. used to

表示过去的习惯动作或状态，现在不复发生或存在。疑问式和否定式有两种。

He used to live in the countryside, but now he lives in the city. 他过去住在乡下，现在住在城里。 He didn’t use to smoke cigarettes.

He usedn’t to smoke cigarettes.

二、 “情态动词＋现在完成式”

“情态动词＋现在完成式”是一种较活跃的语法现象，在各种考试中屡见不鲜。现将其用法归纳如下： 1. 对过去行为发生的可能性的推测

1）“must／may ／might ＋现在完成式”表示对过去行为是否发生的可能性程度不同的肯定推测。

①“must＋现在完成式”这一用法是指说话人对过去所发生的事情的肯定推 断，含有逻辑上的必然性。例如： He must have gone to the clinic．他一定是去医务室了。 They started early this morning

；

they must have arrived by now．他们一大早就启程了，现在一定到了。

②“may ＋现在完成式”表示从现在看来过去可能发生某事。可译为“曾经”、“一度”、“也许”等。例如： He may have missed the train．他可能没有赶上火车。 ③“might ＋现在完成式”表示“可能、也许、已经”，但事实上并未如此。例如：

I might have come to a wrong conclusion．我可能得出了错误的结论。

2) 表示对过去行为可能性的否定推测

①“could ／can not＋现在完成式”表示以现在的眼光看来，过去不可能发生的事。可译为“不可能或不至于”。例如： They couldn’t have left so soon．他们不可能那么早就走了。 They can’t have missed the way．（They’ve been to the zoo before．）他们不可能迷路。（暗含他们以前去过动物园。） I can’t have seen him．我不可能见过他。

②“may not ＋现在完成式”表示“不一定发生过、未必发生过”等。

He may not have visited his parents. 他可能没有看过他的父母。

③“might not ＋现在完成式”表示“不一定就、也可能不、未免有点不”。

They might not have come here. 他们也可能没来过这儿。

2. 表示说话人的语气 1) 表示委婉批评

①“could ＋现在完成式”含有埋怨或训斥的口气。例如： I could have lent you the money．我本来可以把钱借给你的。 Why didn’t you ask me？你为什么没有向我借呢？ ② might ＋现在完成式

You might have been more careful．你本可以再细心一些。

2) 表示惊奇或怀疑

“could ／can ＋现在完成式”常用在疑问句中。例如： Where（can）could they have gone？他们可能到哪里去了呢？ How could they have forgotten such an important meeting？他们怎么能忘记这么重要的会议呢？

3. 表示说话人认为过去的行为应该或不应该发生 1) “should ／ought to ＋现在完成式”表示说话人认为该做而实际未做的事。 例如：

They ought to have done that but they didn’t．他们本应该这样做。

He should have told me the news earlier．他本应该早些告诉我这消息。

2)“should not／ought not to ＋现在完成式”表示过去做了不该做的事。例 如：

You oughtn’t to have done that．你这么做是不应当的。 You should not have gone up to college so soon．（But you did．）你本不应该这么早就上大学的。

They shouldn’t have come．他们本不应该来。

4. 表示不必要性。

表示说话人对过去已做的事情持否定态度，或认为此事根本

没必要做。常用句式为“needn’t ＋现在完成式”。例如： I needn’t have hurried．我大可不必这么急。

The war needn’t have cost mankind so many lives．-It needn’t have happened．在那场战争中本来不必有那么多人丧生，不仅如此，本来就是一场不必要的战争。

讲练结合：

1. I told Sally how to get here, but perhaps I _______ for her. A. had to write it out

B. must have written it out

C. should have written it out D. ought to write it out

2. —There were already five people in the car but they managed to take me as well.

—It _______ a comfortable journey. A. can’t be

B. shouldn’t be

D. couldn’t have been

C. mustn’t have been

3. It’s nearly seven o’clock. Jack _______ be here at any moment. A. must

B. need

C. should D. can

4. Johnny, you _______ play with the knife, you _______ hurt yourself.

A. won’t; can’t

B. mustn’t; may D. can’t; shouldn’t

C. shouldn’t; must

5. The fire spread through the hotel very quickly but everyone _______ get out. A. had to

B. would

C. could

D. was able to

6. —When can I come for the photos? I need them tomorrow afternoon.

—They _______ be ready by 12:00. A. can

B. should

C. might

D. need

7. —I stayed at a hotel while in New York. —Oh, did you? You _______ with Barbara. A. could have stayed C. would stay

B. could stay

D. must have stayed

8. —Are you coming to Jeff’s party?

—I’m not sure. I _______ go to the concert instead. A. must

B. would

C. should

D. might

9. I was really anxious about you. You _______ home without a word.

A. mustn’t leave

B. shouldn’t have left D. needn’t leave

C. couldn’t have left

10. —Is John coming by train?

—He should, but he _______ not. He likes driving his car.

A. must

B. can C. need D. may

【答案解析】

1. C。“ought to / should have+过去分词”表示后悔当初该做但却没做某事。“…也许我本该把详细地址写给她的。” 2. D。“couldn’t have+过去分词”表示对过去情况的推测。既然小汽车上“已有五人”，且是“设法”才把你带去的，如此拥挤，旅途当然“不可能”舒服。

3. C。nearly 暗示“时间不早了”，Jack“按理应当(should)随时(at any moment)”都有可能到达这里。must 语气过强；can 一般不用于肯定推测；need 意义不通，也不用于肯定句。 4. B。mustn’t(不许、千万不)表示禁止。may 表示可能性。句意为“你千万不要玩刀子，可能会弄伤自己的”。

5. D。表示过去具体某次“能够”做成某事只能用 was / were able to 而不用could。

6. B。should 表示按理应当，大概。can 一般不用于肯定推测；用 might 语气太不肯定，顾客可能走掉。

7. A。could have done 表示本可以做但却没有做的事。句意为“你本来可以住在 Barbara 那儿的”；而 must have done 只

表示有把握的肯定推测，这与前面具有疑问语气的 Oh, did you?不符。

8. D。语境明显提示“我可能(might)要去听音乐会” (from www.yygrammar.com)。

9. B。表示轻微的责备，句意为“我真的好担心你啊。你当时本不该不说一声就离开家的”。

10. D。由“他自己喜欢开车”这一习惯推断，“他可能不会(may not)坐火车来”。can not“不可能”，语气太肯定。

表示有把握的肯定推测，这与前面具有疑问语气的 Oh, did you?不符。

8. D。语境明显提示“我可能(might)要去听音乐会” (from www.yygrammar.com)。

9. B。表示轻微的责备，句意为“我真的好担心你啊。你当时本不该不说一声就离开家的”。

10. D。由“他自己喜欢开车”这一习惯推断，“他可能不会(may not)坐火车来”。can not“不可能”，语气太肯定。

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