情态动词1

情态动词的用法

I.教学目标

让学生掌握情态动词的用法

II.学习重难点

让学生熟练掌握情态动词的各个句型

III.教学过程

一．分类：

1.只做情态动词：can（could）、may（might）、must....后接动词原形。

2.可做情态动词又可做实义动词。如：need，dare

3.具有情态动词特征：have（has，had）to，used to（过去常常）。

二．情态动词的用法：情态动词后接动词原形

1.must的用法

1）must意为“必须；应该；一定”。表示说话人的主观意志，表示必须要做的。如：

We must finish reading the book in two weeks. 我们必须在两周内看完这本书。

2）表示说话人对事物的推测，语气比may肯定，只用于肯定句中。Must be译为“一定是”如：

Mr. Liu must be in the office. 刘老师一定在办公室。

3）用must提问时，如果是否定回答，多用needn’t或don’t have to，表示“不必，没必要”，而mustn’t表示“绝对不行，不可以，禁止”的意思。如：

---Must I finish my homework now?

---Yes,you must. ---No,you needn’t/don’t have to

4）have to意为“必须；不得不”，有人称、时态和数的变化，后跟动词原形，表示客观需要。如：

When I was your age，I already had to work.

2.can的用法：

1）can意为“能；会；可以”。表示能力，其否定式是cannot=can’t。如：She can sing. 她会唱歌。

2）表示请求许可。Can I ... ? 意思是“我可以……吗？”，较口语化。

3）can的过去式是could，如：Lucy could swim at the age of five. 露西五岁时就会游泳了。

could也可表示较can更为委婉的语气。如：Could you help me? 帮帮我好吗？

4）can表示推测时，常用于否定句和疑问句中。Can’t be“不可能是”，若是疑问句，其肯定回答用may或must。

如：—Where can it be? 它会在哪里呢？—It may/must be in your desk . 它可能/一定在你的课桌里。

否定回答：It can’t be in your desk.它不可能在你的课桌上。

3.may的用法：

1）may意为“可以；可能”。表示请求、许可。

如：May I look at your CD player? 我可以看一下你的CD机吗？

2）表示可能性（说话人的猜测），常用于肯定句中。如：

Your sister may be waiting for you now. 你妹妹可能现在正在等你呢。

3）以may引起的一般疑问句，否定回答多用mustn’t；

—May I come in? 我可以进来吗？—No, you mustn’t. 不，不行。

4.need的用法：

1)need作情态动词时，意为“需要”，后接动词原形，常用于疑问句和否定句中，否定形式：needn’t,疑问句：Need提前如：You needn’t try to explain.

Need I explain it?

2)need作为实义动词时，后接动词不定式to do，有人称和数的变化。如：

She needs to come tomorrow.

He (不需要）borrow money.

Do they______________(需要）do homework today？

5.had better的用法：

had better（not）do sth 最好（不要）做某事

如：You’d better _______(stay) at home.

You’d better __________(not watch) TV.

练习：

( ) 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