Grammar and usage(2): Modal verbs: comparisons优质课教案设计

情态动词

情态动词为高考重点考查项目，对学习情态动词的要求是了解情态动词各自的基本意义及用法；掌握情态动词表示推测的用法（其中重点是对表过去推测的用法）；注意带有情态动词的反意疑问句的用法。

情态动词的特征：本身有词义，不能独立作谓语，只能和动词原形一起构成谓语；后接动词不定式一律不带to；不随人称和数的变化。

一、情态动词的基本意义及用法进行讲解

（一）can 与could用法对比表

对比点

can could I couldn’t understand what he said at all. He said I could borrow his bike. We thought the story could not be true. How could you be so careless? 表“能力”

Can you lift this heavy box? 表“许可”

You can use a different material instead. 表“怀疑”

No, no, it can’t be true. What on earth can this mean? could代替

can，表示语气更为婉转。

can 与

be able to

eg. Could I use your bike?

Yes, I can can (能够)=be able to(仅表能力时)，但be able to 表示经过努力后，才得以做到，且有更多的时态。

He was a good swimmer, so he ________ swim to the river bank when the boat sank. A. could

B. might

C. shall

D. was able to

（二）may与

might用法对比表

对比点

1.表“询问”

2.表“允许”

3.表“可能”“或许”

may May I …?(=Can I …?) You may take the boy there. She may nor like this place. May I…?的答语。

2.may可表示期望或祝愿

注：

May you succeed ! 3.may (might)用于目的状语从句中

（三）must与have to的用法对比表

对比点

must （主观看法）必须；没有过去式，可do according to what he said. 2.疑问句

Must I …? Do you have to go today? have to （客观需要）不得不，有多种时态。It’s Might Might I …? (=Could I…?) (但比用may 更客气) He told me he might come. (might 与told相呼应) I’m afraid he might not like this play. 肯定：Yes, you may. 否定：No, you mustn’t 不行（语气强硬）

No, you may not 或No, you’d better not. The emperor gave them some gold in order that they might begin their work at once. 1.表“必须”

用于间接引语中。He told me I must raining heavily, we can’t go now.

Yes, you must.（一定）

No, you needn’t./ you don’t have to.(不必) （四）need与dare的用法对比表

对比点

1.情态动词+动词原形

1）否定式

2）疑问式

need He need not (needn’t)go. ----Need we do it again? Yes, we do. 否定句：You don’t have to worry about that. dare He dare not say so. Dare she go out alone at night? How dare you say I’m unfair? If he dare do that, he’ll be punished.(条件句) I dare say.(固定用法) ---No, you needn’t do it again. 2.行为动词+带to不定式

1）肯定式

2）否定式

3）疑问式

3. did not need to do 表示过去没有必要做

对比点

He needs to go. He doesn’t (does not)need to go. Does he need to do it again? He dares to say. He does not(doesn’t)dare to say. If you dare to jump into the water No, he doesn’t need to do it again. from here, so dare I . She didn’t need to attend the meeting yesterday, and she stayed with her children.(她没有参加) should 表劝告、建议

You should listen to the doctor’s advice. We should learn from Zhang Hua.

ought to 表示“有责任有必要”做某事

You ought to finish your work before you go home. We ought to help each other. 表示“非常可能”的事，可译为“总应该”

If we start to work right now, we ought to finish it before lunch.(午饭前应当能干完) （五）should与ought to用法对比表

1.表“应该”

2.表“估计”

They should get home by now.

注：

1.should还可在虚拟语气中的使用

2.注意：ought to的疑问式及否定式

---Ought he to go?

---Yes, I think he ought to. No, he oughtn’t to.

否定式：ought not to a或oughtn’t to do(不说ought to not do) 反疑问句：oughtn’t ______? （六）shall与will的用法对比表

Shall Will 1.征询对方意见或请求指示，用于第一、询问对方的意思或向对方提出要求：

三人称：

Shall I (we)…? Shall he (she)…? Where shall I (we)wait for you? 2.表示说话人的“意愿”有“命令”“警告”“强制”“允诺”“决心”等，用于第二、三人称，要重读。

You shall do what I tell you ( to do). 我叫你干什么你就干什么。

Everything shall be done to save the ship. 一定要竭尽全力来拯救这艘船。

（七）used to与would用法对比表

used to Will you(please)…? Won’t you…? Would you like to…?(用would替代will更客气) ---Won’t you go and see the film?你不去看电影吗？---Yes, I think I will. 不，

我想去。

表示“意志”“意愿”，用于各种人称：

I won’t do anything you don’t like. 我不会做任何你不喜欢的事。

Would表示过去时间的“意志”“意愿”

Shylock would not take the money earlier. 夏洛克先前是不肯要钱的。

would 1.只表示过去动作的重复，有明确的时间状语

I would go to see my grandfather on Sunday when he was in the middle school. 2.would 后只接表动作的动词，不接表认识或状态动词

He used to be nervous in the exam. 1.表示过去的动作、状态，重在与现在情况的对比，不一定要有时间状语。

I used to play cards a lot, but now I seldom play. My hometown is not what it used to be. 2.表示过去的习惯有时可互换：

When we were very young, we used to / would go skating every winter. 表示过去的次数时，不能使用：

( √）We went to the Great Wall five times when we were young. (

X

) We used to go / would go to the Great Wall five times when we were young. 注：used to do的否定式：usedn’t to do 或didn’t use to do (usedn’t也可写作usen’t) 疑问式：

Did you use to do ?

Didn’t you use to do?

Used you to do?

Usedn’t you to do? 二、情态动词表推测的意义：

（一）大多数情态动词（除表‘能力、许可、意志’外），都可表示推测，其程度有差异。按其可能性程度的高低排列为：

Must ﹥will ﹥would ﹥ought to ﹥

should ﹥

can ﹥

could﹥

may ﹥

might

肯定

完全可能

很可能

可能

有可能

（二）注意区分情态动词的否定的含义：

may not或许不、可能不

might not可能不

can’t 不可能

mustn’t不许、禁止

shouldn’t不应该

needn’t 不必

（三）情态动词表推测具体运用：情态动词可以对现在、进行、过去推测

S主+情态动词+be+adj S主+情态动词+be+n 对“性质”“特征”的推测

对“职业”“事物”的推测

S主+情态动词+V原

S主+情态动词+be+V-ing S主+情态动词+have+PP 对经常性行为的推测

对进行着的行为的推测

对过去的行为的推测

特别提醒：情态动词表推测时，can只能用于否定句和疑问句，must只能用于肯定句（它的否定句和疑问句其实就用can来代替了）。如句中有情态动词

+ 完成时，定是对过去的推测。

句中如有表示不肯定的话语，如：I am not sure; I don’t know 之类，常选may /might的各种形式

（四）记忆下列几组表示反劝的特殊的表推测的形式

1.could + have + PP表示本来能做到，但事实上没有做到

2.couldn’t +have + PP表示本来不能做到，但已经做到了

3.needn’t + have + pp表示本不必做的，但已经做到了。

4.should/ought to +have + PP表示

The plant is dead. I should/ought to have given more water. 该做而没有做

5.shouldn’t/ oughtn’t to +have + PP表示不该做而做了

（五）记忆下列对比表：

must只能用于肯定句（它的否定句和疑问句其实就用can来代替了）

1.must + have + PP 表示对过去肯定的推测，译为“一定是，准是”

2.can + have + PP 表示对过去的推测（限于问句中）

Can she have said so? 他可能这样说吗？

3.can’t + have + PP 表示对过去的否定推测

三、情态动词表推测的反意疑问句

情态动词表推测的反意疑问句，简单来说，就是以情态动词后的时态为淮，如句子里有明确的时间状语，则以其为准。以

must 为例：

eg. 1.You must be hungry now, aren’t you?

2.He must be watching TV, isn’t he ?

3.Tom must have lived her for a long time, hasn’t he ? 4.She must have arrived yesterday, didn’t she? 注：如选择题中（以She must have arrived yesterday, didn’t she？为例）既有didn’t she又有hasn’t she则以didn’t she？为最佳答案。

巩固练习：

1.I often see lights in that empty house. Do you think I

report it to the police? A. should

B. may

C. will

D. can 2.---The room is so dirty.

we clean it? He cannot have said such a foolish thing. The road is wet. It must have rained yesterday. You oughtn’t to / shouldn’t have taken her bike without permission. He could have finished the task on time, but the heavy snow came. She could not have covered the whole distance, but in fact she arrived ahead of time. She needn’t have attended the meeting yesterday, but she did.

---Of course. A. Will

B. Shall

C. Would

D. Do 3.My English-Chinese dictionary has disappeared. Who

have taken it? A. should

B. must

C. could

D. would 4.When he was there, he

go to that coffee shop at the corner after work every day. A. would

B. should

C. had better

D. might 5.---The computer is still on, could you have forgotten to turn it off?

---Yes, I

. A. could have

B. could

C. must

D. might have 6.Jenny

have kept her word. I wonder why she changed her mind. A. must

B. should

C. need

D. would 7.Helen

go on the trip with us, but she isn’t quite sure yet. A. shall

B. must

C. may

D. can 8.---There were already five people in the car, but they managed to take me as well. ---It

a comfortable journey. A. can’t

B. shouldn’t be

C. must have been

D. couldn’t have been 9.---Is John coming by train? ---He should, but he

not. He likes driving his car. A. must

B. can

C. need

D. may 10.---I heard they went skiing in the mountains last winter. ---It

true because there was little snow there. A. may not be

B. won’t be

C. couldn’t be

D. mustn’t be

11.I was really anxious about you. You

home without a word. A. mustn’t leave

B. shouldn’t have left

C. couldn’t have left

D. needn’t leave 12.I wonder how he

that to the teacher. A. dare to say

B. dare saying

C. not dare say

D. dared say 13.---Excuse me, but I want to use your computer to type a report. ---You

have my computer if you don’t care of it. A. shan’t

B. might not

C. needn’t

D. shouldn’t 14.---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 15.---Who is the girl standing over there? ---Well, if you

know, her name is Mabel. A. may

B. can

C. must

D. shall 16.---I didn’t go to see the doctor yesterday. ---But you

. A. ought to

B. should

C. ought to go

D. ought to have

17.It has been announced that candidates

remain in their seats until all the papers are collected. A. can

B. will

C. may

D. shall 18.I would love

to the party last night, but I had to work extra hours to finish a report. A. to go

B. to have gone

C. going

D. having gone 19.In fact, you

have shown me to this station—you know, I’m not a new comer. A. couldn’t

B. shouldn’t

C. needn’t

D. mustn’t 20.---Guess what? I drove my new car at a speed of 100 km this afternoon. It was fun. ---Were you crazy? You

yourself. A. can kill

B. might kill

C. would have killed

D. could have killed

21.The fire spread through the hotel very quickly but everyone

get out. A. had to

B. would

C. could

D. was able to 22.---Are you coming to Bob’s party? ---I’m not sure. I

go to the concert instead. A. must

B. would

C. should

D. might 23.They must have taken party in labor yesterday,

? A. didn’t they?

B. mustn’t they?

C. haven’t they?

D. needn’t they? 24.---Be sure to get there on time,

you? ---Of course, we

. A. will; will

B. won’t; shall

C. don’t; do

D. can; must 25.Although diet drinks, such as diet cola, don’t contain so much sugar and calories, they

replace healthy drinks in the diet. A. can not

B. may not

C. should not

D. mustn’t 26.---Do you think the rain will affect the results of the football game? ---Well, the players are used to such rainy weather, so it

make any difference to them. A. shouldn’t

B. needn’t

C. mustn’t

D. shan’t 27.---Daddy, would you buy me an MP3 player if I do well in the first English speech contest? ---I

, I promise. A. would

B. will

C. shall

D. do 28.---He seems to be a student. ---No, he

. A. used to

B. used to be

C. used to have

D. used to have been 29.Johnny, you

play with the knife, you

hurt yourself. A. won’t; can’t

B. mustn’t; may

C. shouldn’t; must

D. can’t; shouldn’t 30.---

I go back before lunch? ---No, I don’t think you

. A. Need; must

B. Do; need to

C. Must; have to

D. May; ought to