一．情態(tài)動(dòng)詞的用法

1. can 用法

1）表示能力，與be able to同義，但can只用于現(xiàn)在時(shí)和過去時(shí)，be able to可用于各種時(shí)態(tài)。

Two eyes can see more than one.

注：Can you ? Yes, I can / No,I cant.

2).表示允許、請(qǐng)求

用could比can 語氣更加委婉客氣，常用于could I /you ..?句型中，若表示同意時(shí)，用can回答而不用could .

Could I borrow the book ? No, you cant .

3）。表示推測 可能常用于否定句或疑問句中。（cant表示一定不是）

It cant be true .

Can it be true ?

2. may 用法

1）表允許，請(qǐng)求= can

表示許可或征求對(duì)方的許可，常于第一人稱連用。

注：May I .? Yes ,you may No, you cant / mustnt .

在回答以may引起的問句時(shí)，多避免用這個(gè)詞，而用其它方式，如Yes, please. / Certainly.

2）表推測，可能、也許。常用于肯定句中。

Maybe he knows the news .=

He _____ _____ the news.

3. must

1）表示義務(wù)。意為必須（主觀意志）。

We must do everything step by step.

注：Must I .? Yes, you must / No,you neednt(dont have to ).

--Must we hand in our exercisebooks now?

--No, you neednt. / No, you dont have to.

2）mustnt 表禁止、不允許。

You mustnt talk to her like that.

3）表示揣測。意為想必、準(zhǔn)是、一定等，只用于肯定句。否定、疑問句中must改為can .

He must be ill. He looks so pale.

Shes wearing a diamond necklace. She must have a lot of money.

注：must表推測時(shí)，其反義疑問句與must后面的動(dòng)詞一致。

There must be something wrong ,____ ____?

4.need的用法

need既可用作情態(tài)動(dòng)詞，也可用作實(shí)義動(dòng)詞。用作情態(tài)動(dòng)詞時(shí)，主要否定句或疑問句中。用作實(shí)義動(dòng)詞時(shí)，可用于各種句式。

1).用作情態(tài)動(dòng)詞，用于否定句和疑問句中。

a).Need I .? Yes , you must / No, you neednt .

Need we finish the work today ?Yes you __?

A.need B.can C. may D.must

b).need + do sth . 變否定句：neednt do sth

變疑問句：Need sb do sth ?

2).用作實(shí)義動(dòng)詞

a).need + to do sth . We need _______(buy) some school things .

變否定句：dont /doesnt /didnt +need to do sth .

變疑問句：Do / Does /Did sb + need to sth ?

Yes , do/ does / did No, sb dont / doesnt /didnt .

You dont need to do it yourself.

b).當(dāng)主語是物時(shí)。Sth + need + doing sth = Sth +need to be done .

The table needs painting . =The table needs _____ _____ _____ .

5.had better 的用法

1). had better + 動(dòng)詞原形 = Its best to do sth .

You had better ______ (stay )at home . = _____ ______ ______ stay at home .

2). Had better not +動(dòng)詞原形

We had better ________(not play ) the computer games .

6.must 與have to

1).一般情況下，兩者可互換。 must = have to

2).must 必須，應(yīng)該表示說話人的主觀看法，即說話人認(rèn)為必須干某事。（內(nèi)在原因）

have to 必須，不得不強(qiáng)調(diào)客觀需要，即外界因素迫使某人不得不干某事。（外界原因）

I cant stop playing the computer games . For your health ,Im afraid you ______.

A.can B.may C.must D.had to

二．情態(tài)動(dòng)詞后跟完成式和進(jìn)行式的用法

1.情態(tài)動(dòng)詞后跟完成式，表原本應(yīng)該干某事，而實(shí)際上沒干

I should have finished the work earlier.

He isnt here. He must have missed the train.

2. 情態(tài)動(dòng)詞后跟進(jìn)行式，表示想必正在，可能正在，應(yīng)當(dāng)正在等意。

Its twelve oclock. They must be having lunch.

They may be discussing this problem.

He cant be telling the truth.

She shouldnt be working like that. Shes still so weak.

三．情態(tài)動(dòng)詞的同義轉(zhuǎn)換.

1.can = be able to

2.must = have to

3.neednt = dont have to

4.need do sth = need to do sth .

一．情態(tài)動(dòng)詞的用法

1. can 用法

1）表示能力，與be able to同義，但can只用于現(xiàn)在時(shí)和過去時(shí)，be able to可用于各種時(shí)態(tài)。

Two eyes can see more than one.

注：Can you ? Yes, I can / No,I cant.

2).表示允許、請(qǐng)求

用could比can 語氣更加委婉客氣，常用于could I /you ..?句型中，若表示同意時(shí)，用can回答而不用could .

Could I borrow the book ? No, you cant .

3）。表示推測 可能常用于否定句或疑問句中。（cant表示一定不是）

It cant be true .

Can it be true ?

2. may 用法

1）表允許，請(qǐng)求= can

表示許可或征求對(duì)方的許可，常于第一人稱連用。

注：May I .? Yes ,you may No, you cant / mustnt .

在回答以may引起的問句時(shí)，多避免用這個(gè)詞，而用其它方式，如Yes, please. / Certainly.

2）表推測，可能、也許。常用于肯定句中。

Maybe he knows the news .=

He _____ _____ the news.

3. must

1）表示義務(wù)。意為必須（主觀意志）。

We must do everything step by step.

注：Must I .? Yes, you must / No,you neednt(dont have to ).

--Must we hand in our exercisebooks now?

--No, you neednt. / No, you dont have to.

2）mustnt 表禁止、不允許。

You mustnt talk to her like that.

3）表示揣測。意為想必、準(zhǔn)是、一定等，只用于肯定句。否定、疑問句中must改為can .

He must be ill. He looks so pale.

Shes wearing a diamond necklace. She must have a lot of money.

注：must表推測時(shí)，其反義疑問句與must后面的動(dòng)詞一致。

There must be something wrong ,____ ____?

4.need的用法

need既可用作情態(tài)動(dòng)詞，也可用作實(shí)義動(dòng)詞。用作情態(tài)動(dòng)詞時(shí)，主要否定句或疑問句中。用作實(shí)義動(dòng)詞時(shí)，可用于各種句式。

1).用作情態(tài)動(dòng)詞，用于否定句和疑問句中。

a).Need I .? Yes , you must / No, you neednt .

Need we finish the work today ?Yes you __?

A.need B.can C. may D.must

b).need + do sth . 變否定句：neednt do sth

變疑問句：Need sb do sth ?

2).用作實(shí)義動(dòng)詞

a).need + to do sth . We need _______(buy) some school things .

變否定句：dont /doesnt /didnt +need to do sth .

變疑問句：Do / Does /Did sb + need to sth ?

Yes , do/ does / did No, sb dont / doesnt /didnt .

You dont need to do it yourself.

b).當(dāng)主語是物時(shí)。Sth + need + doing sth = Sth +need to be done .

The table needs painting . =The table needs _____ _____ _____ .

5.had better 的用法

1). had better + 動(dòng)詞原形 = Its best to do sth .

You had better ______ (stay )at home . = _____ ______ ______ stay at home .

2). Had better not +動(dòng)詞原形

We had better ________(not play ) the computer games .

6.must 與have to

1).一般情況下，兩者可互換。 must = have to

2).must 必須，應(yīng)該表示說話人的主觀看法，即說話人認(rèn)為必須干某事。（內(nèi)在原因）

have to 必須，不得不強(qiáng)調(diào)客觀需要，即外界因素迫使某人不得不干某事。（外界原因）

I cant stop playing the computer games . For your health ,Im afraid you ______.

A.can B.may C.must D.had to

二．情態(tài)動(dòng)詞后跟完成式和進(jìn)行式的用法

1.情態(tài)動(dòng)詞后跟完成式，表原本應(yīng)該干某事，而實(shí)際上沒干

I should have finished the work earlier.

He isnt here. He must have missed the train.

2. 情態(tài)動(dòng)詞后跟進(jìn)行式，表示想必正在，可能正在，應(yīng)當(dāng)正在等意。

Its twelve oclock. They must be having lunch.

They may be discussing this problem.

He cant be telling the truth.

She shouldnt be working like that. Shes still so weak.

三．情態(tài)動(dòng)詞的同義轉(zhuǎn)換.

1.can = be able to

2.must = have to

3.neednt = dont have to

4.need do sth = need to do sth .