2012年成人高考專升本英語備考復(fù)習(xí)(17)
 

情態(tài)動詞有can， could， may， might， must， should， ought to， need， dare， had better， would rather 等。情態(tài)動詞相當(dāng)于助動詞，不能單獨使用，必須再接動詞原型。ought to 整個相當(dāng)于情態(tài)動詞，否定是在情態(tài)動詞后加not，但是ought to的否定是ought not to.

　　1.can， could

　　表示能力、允許、客觀可能性。

　　She is only four， but she can read.

　　Is there anything that I can do for you?

　　This sort of thing can't go on.

　　I couldn't follow her speech.

　　Could you lend me your bike?

　　Fire can't destroy gold.真金不怕火練

　　2.may， might

　　表示允許、猜測。

　　The dialect of one province may be quite different from that of the next one.

　　Students may not stay out after midnight without written permission.(stay out 在外邊待的很晚)

　　He asked his mother if he might go out to play.

　　"May I open the window?" "Yes， please./ Please don't./ No， you mustn't." (may 如果要否定用mustn't，could和might用在現(xiàn)在時表委婉的說法)

　　3.must

　　表示"肯定"、"準是"，還可以表示"必須"，與have to 意思接近，但must 側(cè)重說明主觀看法，have to 強調(diào)客觀需要。must時主觀表達方式，have to是客觀表達方式。mustn't 表示"千萬不要"、"一定不要".

　　If you must go， at least you wait till the rain is over.

　　Teachers always tell us we must do everything step by step.

　　——Must I go tomorrow?

　　——No， you needn't.(Yes， I'm afraid so. must一般疑問句的否定用needn't來回答)、
        
        　He has to tidy up the room everyday.(tidy up 打掃干凈)

　　(He must tidy up the room everyday.)

　　We have to study a foreign language.

　　You mustn't talk like that to your parents.

　　4.ought to ， should

　　表示應(yīng)該做的事和非?？赡艿氖隆?/p>

　　You ought to go to see a doctor for you don't look well.

　　You shouldn't talk like that.

　　The old man said you ought to tell the police.

　　You oughtn't to smoke so much everyday.

　　The work ought to be finished by next Friday.

　　The book should be available in the bookstore. (available 可得到的)

　　5.need

　　表示"需要".need可以當(dāng)情態(tài)動詞，也可以做實義動詞。

　　Need I come?-Yes， you must.(No， you needn't)

　　All you need do is to say yes to his questions.

　　He said he needn't hurry.

　　need 還可以作實義動詞，后面接動名詞時相當(dāng)于被動結(jié)構(gòu)。

        You don't need to stay.(=You needn't say. )

　　Does he need to know it?(= Need he know it?)

　　needs/ wants/ requires +doing相當(dāng)于被動語態(tài)。

　　The question needs/ wants/ requires discussing.(=needs to be discussed.)

　　My shoes need repairing.(My shoes need to be repaired.)

　　物作主語時need接doing表被動。

　　6.dare

　　表示"敢"，也可以作實義動詞，主要用于否定句、疑問句。

　　The boss is so hot-tempered that no one dare tell him the bad news.(so……that 如此……以至于)

　　Who dare stop you?

　　He doesn't dare to look out of the window.

　　情態(tài)動詞沒有人稱性數(shù)的變化，有人稱性數(shù)變化的一定是實義動詞。

　　She dare not say what she thinks.(=She doesn't dare to say what she thinks.)

　　7.had better

　　表示"最好".否定為 had better not

　　I had better not disturb him.

　　We had better go and see the doctor now.

　　8.would rather

　　表示"寧愿"，后面接從句時，從句的謂語用一般過去時。否定用would rather not.

　　I'd rather not say anything.

　　John would rather work in a company than in a factory.

　　She would rather have the small oranges than the large ones.

　　I would rather you came tomorrow.

　　(would sooner 遲早，后的賓語從句用虛擬語氣，一般過去時。)

　　I would sooner she left the heavy end of the work to someone else.