情态动词教案.doc

新课讲解 情态动词
情态动词的定义: 情态动词是一种本身有一定的词义,表示说话人的情绪,态度或语气的动词,但不能单独作谓语, 只能和其他动词原形构成谓语。
We can be there on time tomorrow. 我们明天能按时去那儿。May I have your name? 我能知道你的名字吗？
Shall we begin now? 我们现在就开始吗？ You must obey the school rules.你必须遵守校规。
情态动词数量不多,但用途广泛,主要有下列:
　can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would) .
情态动词的位置: 情态动词在句中放在谓语动词之前, 谓语动词前若有助动词,则在助动词之前,疑问句中, 情态动词则在主语之前。
　I can see you. Come here. 我能看见你，过来吧。 He must have been away.他一定走了。
　What can I do for you? 你要什么？ How dare you treat us like that！你怎能那样对待我们！
情态动词的特点: 情态动词无人称和数的变化, 情态动词后面跟的动词需用原形,否定式构成是在情态动词后面加 "not"。 个别情态动词有现在式和过去式两种形式, 过去式用来表达更加客气, 委婉的语气, 时态性不强, 可用于过去，现在或将来。
He could be here soon. 他很快就来。 We can't carry the heavy box. 我们搬不动那箱子。
　I'm sorry I can't help you. 对不起，我帮不上你。
１．Can/could
（１）can 一般表示体，脑力方面的能力，意为“能，会（做某事）”，也可用来表示客观的可能性，意为“可以，可能”。例如：He can swim in the river． I can do the work myself．
The boy can sing in English． I can help you with your housework．
（２）can ＼ could 也可以用于疑问句，否定句中表示“猜测”。如：
He can't be at home.他不可能在家。
（３）can还能用来询问或请求一件事可以不可以做，常用于口语中，相当于may。例如：
Can I help you? ＝ May I help you?
can 的否定式是在其后加not， 写为cannot 或can't。例如：You can't stay here you can go home now.
（4）表示能力（体力、知识、技能）。
Can you lift this heavy box?（体力）
Mary can speak three languages.（知识）Can you skate?（技能）
此时可用be able to代替。Can只有一般现在时和一般过去式；而be able to则有更多的时态。
I’ll not be able to come this afternoon.
当表示“经过努力才得以做成功某事”时应用be able to，不能用Can。如：
He was able to go to the party yesterday evening in spite of the heavy rain.
(5)表示请求和允许。
-----Can I go now? ----- Yes, you can. / No, you can’t.
此时可与may互换。在疑问句中还可用could,
might代替，不是过去式，只是语气更委婉，不能用于肯定句和答语中。
---- Could I come to see you tomorrow? ---- Yes, you can. ( No, I’m afraid not )
(6)表示客观可能性（客观原因形成的能力）。
They’ve changed the timetable, so we can go by bus instead. This hall can hold 500 people at least.
(7)表示推测（惊讶、怀疑、不相信的态度），用于疑问句、否定句和感叹句中。
Can this be true? This can’t be done by him. How can this be true?
２．May/ Might
（１）may一般表示“请求，许可，允许”。例如：
—May I come in﹖ —Come in please.
—May I go home now﹖ —Yes, you may.
You may only keep the books for two weeks．这些书你只可以借两个星期。
（２）may可以用来表示“猜测，推测”。例如：
Our head teacher may be in the office． 我们的班主任可能在办公室。
（３）may还能用来表示“希望，祝愿，渴望，请求和应该”。用于祈使句，表示祝愿。例如：
May you be happy！祝你幸福！ May you succeed!
（4）表示请求和允许。might比 may语气更委婉，而不是过去式。否定回答时可用can’t
或mustn’t，表示“不可以，禁止”。
----Might/ May I smoke in this room? ---- No, you mustn’t.
---- May/Might I take this book out of the room? ---- Yes, you can. (No, you can’t / mustn’t. )
用May I...？征徇对方许可时比较正式和客气，而用Can I...？在口语中更常见。
表示推测、可能性（不用于疑问句）。might不是过去式，它所表示的可能性比may小。
He may /might be very busy now. Your mother may /might not know the truth.
３．Must/ have to
（１）must表示义务，禁止和推测，意思是“必须，应该，应当，一定是，务必要”等。例如：
I must do my homework at once． We must speak more English．
You must help each other． It's ten now my mother must be angry.
（２）在回答must的疑问句时，其否定形式多用needn't来表示“没必要，不许”。例如：
—Must she answer the question in English﹖ —No, she needn't．
注意：mustn't 经常表示绝对禁止，语气强烈。如： You mustn't do it again．你再也不能这样做了。
（３）must在表示猜测，推测时，否定式常用can't代替。例如：
The students of Class Three must be having a good time in the park．三班的学生一定在公园玩得很高兴。
Tom must be in the classroom． 汤姆一定在教室里。 He cannot be ill．他不可能生病。
（4）must是说话人的主观看法， 而have to则强调客观需要。Must只有一般现在时， have to 有更多的时态形式。 Her play isn’t interesting, I really must go now. I had to work when I was your age.
3) 表示推测、可能性（只用于肯定的陈述句）
You’re Tom’s good friend, so you must know what he likes best.
Your mother must be waiting for you now.
4 . ought to， should
ought to 和 should 都可译为“应该”，但它们之间还是有点区别。
◆ ought是一个情态动词，意为“应该，理应”表示义务和责任。无人称、时 态和数的变化，后接带to的不定式，如果是ought to have done形式则是表愿望。
   eg：You ought to obey your parents．  他应该服从你的父母。
       It occurred to him that he ought to go and see her．   他曾想到了自己应该去看看她。
          You ought to have locked the door when you went out．  你外出的时候应该上门。
◆ should作情态动词时，意为“应该，应当”表示建议，无人称、时态和数的变化，它的语气比ought to弱；should have done 形式多用于与过去相反的虚拟结构中。
    eg：You should do it for your own good．为了你自己的好处，你应该做那件事。
           You shouldn't come to such a decision hastily．   你不应该仓促(草率)地做出这样一个决定。
          I should have bought it if I had enough money．如果我当时有足够的钱的话，我就会把它买下来
5. shall
1) shall 用于第一人称，征求对方的意见。 What shall we do this evening?
2) shall 用于第二、三人称，表示说话人给对方的命令、警告、允诺或威胁。
1. You shall fail if you don’t work hard.(警告)
2. He shall have the book when I finish it.(允诺) 3. He shall be punished.(威胁)
6. will, would
1) 表示请求、建议等，would更委婉。 Will / Would you pass me the ball, please?
2) 表示意志、愿望和决心。1. I will never do that again. 2. They asked him if he would go abroad
3) would表示过去反复发生的动作或某种倾向。would表示过去习惯时比used to正式，且没有“现已无此习惯”的含义。1. During the vacation, he would visit me every other day. 2. The wound would not heal.
4) 表示估计和猜想。 It would be about ten o’clock when she left home.
四、 情态动词的辨析
（一）can 和could
1.表示能力，意思是“能，会”。 2.表示请求、允许，意思是“可以”。
3.表示可能性。通常用在否定或者疑问句中.could 为can的过去式，比can的可能性要小。如：
He can swim, but i can't. You can use my dictionary.
The coat can't be hers. Hers is white. Could you help me, please?
4.表能力时，could 和can枝用于现在时和过去时，其他时态一般用be able to来表达。如：
With the teacher's help, i shall be able to speak English well.
（二）shall, should, ought to ,must, have to
1.shall表示征询意见，主要用于第一人称的疑问句中。如： Shall i take you to the hospital? Shall we go now?
2.should 和ought to
都有“必须，应该”的意思。当强调道义或法律所规定的职责时用ought to; 如果是说话者的一种主观看法时，则用should.如：
We should speak English in our English class every day. You ought to bring the children here.
3.must 和have to
都有“必须”的意思，must是表示说话者的主观愿望；have to 则侧重于客观上的必要，意为“不得不，只得” ，如： I must take good care of the pets. When the traffic lights turn red, i have to stop the car.
4.must还表示推测，意为”一定，准是“。如：
The lady must be a doctor.
5.should 和ought to在“should/ ought to + have+过去分词”结构中，表示应该做某事但实际上未做。其否定机构是“should not / ought not to + have+过去分词” ，表示不应该做某事但实际上做了。如：
You should have been here yesterday. You ought not to have taken the book out of the reading-room.
6.在 “must + have + 过去分词”结构中，表示对过去的肯定猜测，意思是“肯定做过某事”。 如：
He must have told my parents about it.
（三）will 和would
1.表示决心、愿望。意思是“愿意，将会” 。如： I'll do my best to catch up with them.
I'll never do it again; that's the last time. He would help me with my maths.
2.在疑问句中，will 和would都可以表示说话人向对方提出请求或询问，但是would比will更婉转。如：
It's hot. Will you open the window? Will you help me to work it out?
（四） 、may 和might
1.表示可能性，意思是“可以” ，暗含较强的不确定语气。might 比may的可能性更小。如：
She may go there tomorrow. He said he might lend us some money.
2.表示允许或者是征求同意，多用于肯定句和疑问句中。如：
You may take the book home. She might help if she knows the truth.
1． might是may的过去式，语气更加委婉、客气和对可能性的怀疑。如：
2． He told me he might be here on time. He might be alive. Might i borrow any money now?
（五） 、need 和dare
1.need的意思是“需要，必要”。 作情态动词时，后直接跟动词原形，变否定时，直接在后面加“not”，变疑问句时，直接提到主语之前。如：You needn't come if you are busy. Need i hand in the paper this week?
2.dare的意思是“敢” 。作情态动词时，后跟动词原形，变否定时，直接在后面加“not”，变疑问句时，直接提到主语之前。如： The little girl dare not speak in public. Dare you catch the worms?
3. need 和dare还可作实义动词用。作实义动词时，与与普通实义动词一样，有第三人称单数形式。变否定时要在前面加“don't, doesn't, 或didn't” 。变疑问句时，不能提前，而是在主语前面加“do, does, 或did” 。如：
She needs a necklace. You don't need to attend the meeting. Do you dare to walk in the dark？
有关情态动词的练习题
1 John___ come to see us tonight, but he isn't very sure yet.
A. may B. can C. has to D. must
2 They ___ do well in the exam.
A. can be able to B. be able to C. can able to D. are able to
3 -May I take this book out?
-No, you___.
A. can't B. may not C. needn't D. aren't
4 You___ go and see a doctor at once because you're got a fever.
A. can B. must C. dare D. would
5 -Can you speak Japanese?
-No, I____.
A. mustn't B. can't C. needn't D. may not
1 -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; can't D. may; mustn't
2 -Shall I get one more cake for you, Dad?
-Thanks, but you___, I've had enough.
A. may not B. must not C. can't D. needn't
3 Even the top students in our class can't work out this problem, so it____ be very difficult.
A. may B. must C. can D. need
4 He isn't at school. I think he ___ be ill.
A. can B. shall C. must D. has to
5 ___ I take this one?
A. May B. Will C. Are D. Do
1. The children___ play football on the road.
A. can't B. can C. mustn't D. must
2 You ___ be late for school again next time.
A. mustn't B. needn't C. don't have to D. don't need to
3 -Must I do my homework at once?
-No, you___.
A. needn't B. mustn't C. can't D. may not
1 His arm is all right. He___ go and see the doctor.
A. has not to B. don't have to C. haven't to D. doesn't have to
2 He had to give up the plan, ___ he?
A. did B. didn't C. does D. doesn't
3 They had to walk here, ___ they?
A. mustn't B. did C. didn't D. hadn't
1 He had better stay here, ___ he?
A. didn't B. don't C. hadn't D. isn't
2 You'd better___late next time.
A. not to be B. not be C. won't be D. don't be
3 You'd better ___ your hair ___ once a month.
A. had; cut B. had; cutted C. have; cut D. have; cutted
4 You___ ask that man over there. Maybe he knows the way.
A. had better not to B. had not better C. had better D. had better not
1 -Shall we go and visit the History Museum next Sunday?
A. Here you are B. Sorry, I can't C. Yes, please D. Let me try
2 -Why don't you ask Mike to go with us?
-Thanks, ___.
A. I will B. I won't C. lean D. I may
3 -___ I take the newspaper away?
-No, you mustn't. You____read it only here.
A. Must; can B. May; can C. Need; must D. Must; must
1 Excuse me. ___ you please pass me that cup?
A. Do B. Should C. Would D. Must
2 ___ you like to have another try?
A. Could B. Will C. Would D. Do
3 -Would you like to go boating with us?
-Yes, ___.
A. I'd like B. I want C. I'd like to D. I do
1 You___ worry about your son. He will get well soon.
A. needn't B. can't C. mustn't D. have to
2 The poor man needs our help, ___ he?
A. need B. needn't C. does D. doesn't
3 -Must we do our homework first?
-No, you___. You may have a rest first.
A. mustn't B. needn't C. may not D. can't
3、情态动词在虚拟语气中的用法
情态动词用于虚拟语气中表示责备的感情色彩，用法如下：
（1）should have done表示“本来应该做某事而实际上未做”，而shouldn’t have done则表示“本不应该做某事而实际上做了”。如：You should have told me about it earlier.
You shouldn’t have said such words to your parents.
（2）ought to have done也表示“本应该……”而ought not to have done则意为“本不应该……”。如：
You ought to have told me about it earlier.
You ought not to have said such words to your parents.
（3）needn’t have done表示“本无必要做某事而实际上做了”。如：
You needn’t have walked so quickly since time was enough.
（4）could have done表示“本来有可能……而事实上未做到”。如：
I could have come on time, but my car broke on the way.
ù二、精典名题导解
1. I was really anxious about you. You________home without a word.
A.mustn’t have B.shouldn’t have left
C.couldn’t have left D.needn’t have
解析：答案为B。本题考查的是情态动词在虚拟语气中的用法。题目给出的条件是“我确实非常担心你”，因此后面可知应是责备you不应该没说一句话就离开了。
2.—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
解析：答案为D。本题考查情态动词的基本用法。由题目中“I’m not sure”,表明我可能去Jeff’s party，也可能去音乐会，故用might。
3. —Will you stay for lunch?
—Sorry, ____________. My brother is coming to see me.
A.I mustn’t B.I can’t C.I needn’t D.I won’t
解析：答案为B。本题考查表示请求的英语口语，用will来向第二人称提问的疑问结构，是表示一种请求和意愿，是用疑问的形式来表达较为婉转的祈使语气，意思是“请你……，好吗”，对于这种问句的肯定回答是：Suree! Gertainly! Yes, of course. I’d be glad to 等；否定回答通常是：I’m sorry, I can’t. No, I’m afraid I can’t. I’m sorry, but … I’d like to, but …等。注意情态动词表客气的用法及其在一般疑问句中的问与答。
4.—Isn’t that Ann’s husband over there?
—No, it be him I’m sure he doesn’t wear glasses.
A. can’t B. must not C. won’t D. may not
解析：答案为A。本题考查情态动词表推测。问：那边的难道不是Ann的丈夫吗？答：不是。不可能是他，我确信他不戴眼镜。
5.You be tired－you’ve only been working for an hour.
A. must not B. won’t C. can’t D. may not
解析：答案为C。句中破折号后的内容对前一句进行解释说明：你只工作了一个小时，所以你不可能累的。表否定推测时用can’t。A项表禁止（不许），B项表未来，D项表不允许。均不可用，故选C。
6.I often see lights in that empty house. Do you think I report it to the police？
A. should B. whatever C. whichever D. whenever
解析：答案为A。本题考情态动词。在空房子里看到灯光，是一件奇怪而令人生疑的事，故问：你是否认为我应当把这事儿报告给警察？应用A。

情态动词
对现在和未来的推测
对过去的推测
使 用 场 合
must
must + 动词原形
must have done
肯定句
may / might
may / might + 动词原形
May / might have done
肯定句、否定句
can /could
can / could do
Can / could have done
否定句、疑问名（could可用于肯定句）
should
用来表示一种估计的情况“按理会/估计会”should do/be
should have done
肯定句、否定句、疑问句

泗水实验中学高一英语备课组 第 6 页 共 6 页