（原創(chuàng)精品）2013年普通高考英語科語法知識網(wǎng)絡

專題08 情態(tài)動詞和虛擬語氣

I.情態(tài)動詞基本用法

情態(tài)動詞

用 法

否定式

疑問式

簡答式

can

能力（體力，智力，技能）

允許或許可（口語中常用）

可能性（表猜測，用于否定句或疑問句中）

can not / cannot /can’t do

Can…do…?

Yes,…can.

No,…can’t.

could

couldn’t do

may

可以（問句中表示請求）

可能，或許（表推測）

祝愿（用于倒裝句中）

may not do

ay…do…?

Yes,…may.

No,…mustn’t/can’t.

might

might not do

ight…do…?

Yes,…might

No,…might not.

must

必須，應該（表主觀要求）

肯定，想必（肯定句中表推測）

must not/mustn’t do

ust…do…? to.

Yes,…must.

No,…needn’t/don’t have

have to

只好，不得不（客觀的必須，有時態(tài)和人稱的變化）

don’t have to do

Do…h(huán)ave to do…?

Yes,…do.

No,…don’t.

ought to

應當（表示義務責任，口語中多用should）

ought not to/oughtn’t to do

Ought…to do…?

Yes,…ought.

No,…oughtn’t.

shall

用于一三人稱征求對方意見

用于二三人稱表示許諾、命令、警告、威脅等

shall not/shan’t do

Shall…do…?

Yes,…shall.

No,…shan’t.

should

應當，應該（表義務責任）

本該（含有責備意味）

should not/shouldn’t do

Should…do…?

will

意愿，決心

請求，建議，用在問句中would比較委婉

will not/won’t do

Will/Would…do…?

Yes,…will.

No,…won’t.

would

would not/wouldn’t do

dare

敢（常用于否定句和疑問句中）

dare not/daren’t do

Dare…do…?

Yes,…dare.

No,…daren’t.

need

需要,必須（常用于否定句和疑問句中）

need not/needn’t do

Need…do…?

Yes,…must. No,…needn’t.

used to

過去常常（現(xiàn)在已不再）

used not/usedn’t/usen’t to do

didn’t use to do

Used…to do…?

Did…use to do…?

Yes,…used.

No,…use(d)n’t.

Yes,…did.

No,…didn’t.

II.情態(tài)動詞的重點知識

表示“能力、許可”的can和may

表示能力的情態(tài)動詞用can/could

A computer_____think for itself; it must be told what to do.

A.can’t B.mustn’t C.may not D.might not

表示許可時用may/might ,can/could 都可以，但在問句中用could…?或might…？ 以使口氣委婉客氣，其回答一定要用can或may，以使回答口氣明確（must表示一定，必須，mustn’t表示禁止，不許可）。

①—Could I call you by your first name? —Yes, you______

A.will B.could C.may D.might

②Johnny, 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

在肯定句中could不可以用表示過去某一特定場合的能力，而要用was/were able to。

The fire spread through the hotel very quickly but

everyone_____get out.

A.had to B.would C.could D.was able to

表示“推斷、判斷”的can

may,must

在肯定句中都可以用表示可能。在含義上must語氣最肯定,may表示的是事實上的可能性。

Peter______come with us tonight, but he isn’t very sure yet.

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

而can表示的是邏輯上的可能性：

ary is in poor health. She can be ill at any times.

在否定句中只能用can和may。所以can’t時用以代替mustn’t，語氣比may更肯定。中可以翻譯為不可能。

ichael______be a policeman, for he’s much too short.

A.needn’t B.can’t C.should D.may

在疑問句只能用can，不能用may和must。

He may be very busy no Can he be very busy now?

He must be very busy no Can he be very busy now?

need

need作為情態(tài)動詞只有一種形式，只用于否定句和疑問句。

dare

dare作為情態(tài)動詞用時有兩種形式：dare和dared兩個詞形，除了可以用于否定句和疑問句外，還可以用于條從句或表示懷疑的句子中。

If he dare come,I will kick him out. I don’t knohether he

dare say.

注意:He doesn’t dare(to)answer the question.（否定句）

Does she dare(to)enter the dark room?（疑問句）

shall

用于第一人稱：征求對方的意見。

What shall we do this evening?

用于第二、三人稱：警告、命令、允諾、威脅等。

You shall fail if you don’t work harder. 警告

He shall have the book when I finish reading.允諾

He shall be punished.威脅

should

勸告、建議、命令、應該做、道義上的責任。

You should(ought to) go to class right away.

I should(ought to) help him because he is in trouble.

will/would

請求、建議，would比will委婉客氣。

Would you pass me the book?

表示意志、愿望和決心。

I will never do that again.

They asked us if we would do that again

would可表示過去反復發(fā)生的動作或某種傾向。

During the vacation he would visit me every week

The wound would not heal.（傷口老是不能愈合）

would表示估計或猜想。

It would be about ten when he left home.

What would she be doing there?

情態(tài)動詞+have done的用法

could+have done：本可以做而實際上未能做。

You could have done better, but you didn’t try your best.

cannot+ have done：表示對現(xiàn)在或過去行為的否定推測。

He cannot have been to that town.

can+主語+ have done：表示對過去行為的懷疑或不肯定（用在疑問句中）。

Can he have got the book?

might(may)+ have done：對過去發(fā)生的行為不太肯定的推測。

He may not have finished the work.

If we had taken the other road, we might have arrived earlier.

must+ have done：對過去發(fā)生的行為肯定的推測。

其否定式為：cannot have done。

You must have seen the film.

You cannot have seen the film.

needn’t+ have done：本不必要做的而實際上又做了。

You needn’t have watered the flowers,for it is going to rain.

注意：didn’t need to(have to)do：

沒有必要做而實際上也沒有做

I didn’t need to clean the windows.y sister did it 2 hours ago.

should(ought to)+ have done：本應該做而實際上又沒有做。其否定形式表示某中行為不該發(fā)生卻發(fā)生了。

You should have started earlier, but you didn’t.

She shouldn’t have taken away my measuring tape,

for I worked to use it.

注意：He should have finished the work by no（表推測）

虛擬語氣

類 別

用 法

例 句

If引導的

條從句

與現(xiàn)在事實相反

從句動詞：過去式（be用were）

主句動詞：should/would/could/might+do

If he were here, he would help us.

與過去事實相反

從句動詞：had+done

主句動詞：should/would/could/might+have+done

If I had been free,I would have visited you.

與將事實相反

從句動詞：過去式/should+動詞原形/were+to do

主句動詞：should/would/could/might+動詞原形

If it should rain tomorrow, we would not go camping.

省略if的虛擬條句

將虛擬條從句中的were，had,should放到主語之前，構(gòu)成主謂倒裝

①Should he come ,tell him to ring me up.

②Were I you,I would not do it.

③Had I been free,I would have visited you.

混合虛擬條句

不同時間的虛擬：各遵守各的規(guī)則

①If he had listened to me, he would not be in trouble no

②If he had told me yesterday,I should knohat to do no

③If I were you, I would have gone to her birthday party.

虛擬與陳述的混合：各遵守各的規(guī)則

①He could have passed the exam,but he wasn’t careful enough.

②You should have come earlier.The bus left a moment ago.

含蓄虛擬

條句

but for+名詞表示虛擬條

句子或主句中的謂語動詞的形式視具體情況而定。這是考查考生應變能力的最佳試題。

---But for your timely warning,we ______ into great trouble.

---You knoe’re friends.

A. would get B. must have got

C. would have got D. can’t have got

without+名詞表示虛擬條

Without the air to hold some of the sun's heat, the earth at night would be freezing cold.

動詞不定式表示虛擬條

It would be only partly right to follow in this way.
如果用這種方式，僅僅對了一半。

現(xiàn)在分詞表示虛擬條

Having known in time ,we might have prevented the accident.要是及時得知的話，我們也許能阻止這場事故。

過去分詞表示虛擬條

Given more attention, the tree could have grown better.
如果多留心的話，這樹本可以長的更好。

副詞otherwise表示虛擬條

I was too busy at that time.Otherwise,I would have called you.我當時太忙，否則我就給你打電話了。

連詞but連接的句子表示虛擬條

He _____fatter but he eats too little .

A. would become B. would have become

C. must become D. must have become

其它

狀語從句

as if/as though引導的狀語從句中動詞用did或had＋done或would／could／might＋do。

注意：as if/as though引導的狀語從句中也可以用陳述語氣：

當說話者認為所述的是真實的或極有可能發(fā)生或存在的事實時：

It sounds as if it is raining．聽起像是在下雨。
He talks as if he is drunk．從他談話的樣子看他是醉了。

①與現(xiàn)在事實相反

He talks as if he knehere she was．

②與過去事實相反

He talks about Rome as if he had been there before.

③與將事實相反

He opened his mouth as if he would say something.

in order that/so that引導的狀語從句中動詞用can/could/may/ might/ would等+do

Turn on the light so that we can see it clearly.

賓語從句

demand, suggest, order, insist后接的從句中動詞為should+do

He suggested that we not change our mind.

wish后的從句中分別用過去式，過去完成式和should/would+do表示與現(xiàn)在，過去和將情況相反

I wish I could be a pop singer.

I wish I would have gone to Shanghai last month.

主語從句

在It is necessary / important / strange that…

It is suggested / demanded/ ordered / requested that…等從句中，

謂語動詞用should+do

It is strange that such a person should be our friends.

其它

句型中

It is time that…句型中動詞用過去式或should+do

It’s high time that we left/should leave.

would rather所接的從句中動詞用過去式或者過去完成式

I would rather you stayed at home no

If only句型中動詞常用過去式或者過去完成式，表示強烈的愿望

If only our dream had come true!

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