21.7 情態(tài)動(dòng)詞+ have +過(guò)去分詞

　　1) may(might) have + done sth, can (could) have + done sth　表示過(guò)去，推測(cè)過(guò)去時(shí)間里可能發(fā)生的事情。例如：

　　Philip may (might) have been hurt seriously in the car accident. 菲力浦可能在車禍中受了重傷。

　　Philip can (could) have been hurt seriously in the car accident.

　　2) must have +done sth，對(duì)過(guò)去時(shí)間里可能發(fā)生的事情的推測(cè)，語(yǔ)氣較強(qiáng)，具有肯定，諒必的意思。例如：

　　---Linda has gone to work, but her bicycle is still here. 琳達(dá)已經(jīng)去上班了，但她的單車還在這兒。

　　---She must have gone by bus.肯定乘巴士去的。

　　3) ought to have done sth, should have done sth表示本應(yīng)該做某事，而事實(shí)上并沒有做。否定句表示不該做某事而做了。例如：

　　You ought to (should) have been more careful in this experiment. 你當(dāng)時(shí)在做試驗(yàn)時(shí)應(yīng)該更仔細(xì)點(diǎn)。

　　He ought not to have thrown the old clothes away.他不該把舊衣服扔了。(事實(shí)上已扔了。)

　　ought to 在語(yǔ)氣上比should 要強(qiáng)。

　　4) neednt have done sth表示本沒必要做某事，但做了。例如：

　　I dressed very warmly for the trip, but I neednt have done so. The weather was hot.

　　旅行時(shí)，我衣服穿得較多，其實(shí)沒有必要。那時(shí)天很熱。

　　5) would like to have done sth表示本打算做某事，但沒做。例如：

　　I would like to have read the article, but I was very busy then. 我想讀這篇文章，但太忙了一直沒讀。

　　17.8 21.8 should 和ought to

　　除了上述的用法，兩者還可表示想必一定，按理應(yīng)該的意思。例如：

　　I ought to be able to live on my salary. 靠我的薪水，想必也能維持了。

　　It ought to be ready now. 想必現(xiàn)在準(zhǔn)備好了吧。

　　They should be there by now, I think. 現(xiàn)在他們?cè)摰侥莾毫恕?/p>

　　The poems should be out in a month at most. 詩(shī)集估計(jì)最多還有一個(gè)月就要出版了。

　　21.9 had better表示最好，相當(dāng)于一個(gè)助動(dòng)詞，它只有一種形式，它后面要跟動(dòng)詞原形。例如：

　　It is pretty cold. Youd better put on my coat. 天相當(dāng)冷。你最好穿上我的外套。

　　Shed better not play with the dog. 她最好不要玩耍那條狗。

　　had better have done sth表示與事實(shí)相反的結(jié)果，意為本來(lái)最好。例如：

　　You had better have come earlier. 你本該來(lái)得早一點(diǎn)。

　　21.10 would rather表示寧愿

　　would rather do

　　would rather not do

　　would rather than　 寧愿而不愿。

　　還有would sooner, had rather, had sooner都表示寧愿、寧可的意思。例如：

　　If I have a choice, I had sooner not continue my studies at this school. 如果有選擇的余地，我寧可輟學(xué)離開這個(gè)學(xué)校。

　　I would rather stay here than go home. = I would stay here rather than go home. 我寧愿呆在這兒，而不愿回家。

　　典型例題

　　----Shall we go skating or stay at home?

　　----Which ___ do?

　　A. do you rather　　B. would you rather　 C. will you rather　 D. should you rather

　　答案B。本題考查情態(tài)動(dòng)詞rather的用法，would rather +do sth 意為寧愿，本題為疑問(wèn)句，would 提前，所以選B。

　　21.11 will和would

　　注意：1)would like;would like to do = want to 想要，為固定搭配。例如：

　　Would you like to go with me? 想和我一塊去嗎?

　　2)Will you?　Would you like? 表示肯定含義的請(qǐng)求勸說(shuō)時(shí)，疑問(wèn)句中一般用some, 而不是any。例如：

　　Would you like some cake? 吃點(diǎn)蛋糕吧。

　　3)否定結(jié)構(gòu)中用will，一般不用would, wont you是一種委婉語(yǔ)氣。

　　Wont you sit down? 你不坐下嗎?

　　21.12 情態(tài)動(dòng)詞的回答方式

　　問(wèn)句 肯定回答 否定回答

　　Need you? Yes, I must. No, I neednt

　　Must you? No, I dont have to.

　　典型例題

　　1)---Could I borrow your dictionary?

　　---Yes, of course, you____.

　　A. might　B. will　 C. can　 D. should

　　答案C. could表示委婉的語(yǔ)氣，并不為時(shí)態(tài)。答語(yǔ)中of course，表示肯定的語(yǔ)氣，允許某人做某事時(shí)，用can和 may來(lái)表達(dá)，不能用could或might。will 與you連用，用來(lái)提出要求或下命令。should與you 連用，用來(lái)提出勸告。

　　2)---Shall I tell John about it?

　　---No, you ___. Ive told him already.

　　A. neednt　　B. wouldnt　　C. mustnt　　D. shouldnt

　　答案A。neednt 不必，不用。 wouldnt 將不, 不會(huì)的。 mustnt 禁止、不能。 shouldnt　不應(yīng)該。本題為不需要，不必的意思，應(yīng)用neednt。

　　3)---Dont forget to come to my birthday party tomorrow.

　　---______.

　　A. I dont　 B.　I wont　 C. I cant　D. I havent

　　答案B. will既可當(dāng)作情態(tài)動(dòng)詞，表請(qǐng)求、建議、也可作為實(shí)義動(dòng)詞表意愿、意志、決心，本題表示決心，選B。

　　21.13 帶to 的情態(tài)動(dòng)詞

　　帶to 的情態(tài)動(dòng)詞有四個(gè)：ought to, have to, used to, be to, 如加上have got to (=must), be able to，為六個(gè)。它們的疑問(wèn)、否定形式應(yīng)予以注意：

　　Do they have to pay their bill before the end of the month?

　　She didnt use to play tennis before she was fourteen.

　　You ought not to have told her all about it.

　　Ought he to see a heart specialist at once.?

　　ought to 本身作為情態(tài)動(dòng)詞使用。其他的詞作為實(shí)義動(dòng)詞使用，變疑問(wèn)，否定時(shí)，須有do 等助動(dòng)詞協(xié)助。

　　典型例題

　　Tom ought not to ___ me your secret, but he meant no harm.

　　A. have told　B. tell　C. be telling　D. having told

　　答案A。由于后句為過(guò)去時(shí)，告訴秘密的動(dòng)作又發(fā)生在其前因，此地應(yīng)用過(guò)去完成時(shí)，但它在情態(tài)動(dòng)詞 ought to 后，所以用have told。

　　21.14 比較need和dare

　　這兩詞既可做實(shí)義動(dòng)詞用，又可做情態(tài)動(dòng)詞用。作為情態(tài)動(dòng)詞，兩者都只能用于疑問(wèn)句，否定句和條件句。need 作實(shí)義動(dòng)詞時(shí)后面的不定式必須帶to，而dare作實(shí)義動(dòng)詞用時(shí), 后面的to 時(shí)常可以被省略。

　　1) 實(shí)義動(dòng)詞：need(需要, 要求) need + n. / to do sth

　　2) 情態(tài)動(dòng)詞：need，只用原形need后加do，否定形式為need not。例如：

　　Need you go yet? 你要走了嗎?

　　Yes, I must. / No, I neednt.是的，我要走了/不，不急著走。

　　21.7 情態(tài)動(dòng)詞+ have +過(guò)去分詞

　　1) may(might) have + done sth, can (could) have + done sth　表示過(guò)去，推測(cè)過(guò)去時(shí)間里可能發(fā)生的事情。例如：

　　Philip may (might) have been hurt seriously in the car accident. 菲力浦可能在車禍中受了重傷。

　　Philip can (could) have been hurt seriously in the car accident.

　　2) must have +done sth，對(duì)過(guò)去時(shí)間里可能發(fā)生的事情的推測(cè)，語(yǔ)氣較強(qiáng)，具有肯定，諒必的意思。例如：

　　---Linda has gone to work, but her bicycle is still here. 琳達(dá)已經(jīng)去上班了，但她的單車還在這兒。

　　---She must have gone by bus.肯定乘巴士去的。

　　3) ought to have done sth, should have done sth表示本應(yīng)該做某事，而事實(shí)上并沒有做。否定句表示不該做某事而做了。例如：

　　You ought to (should) have been more careful in this experiment. 你當(dāng)時(shí)在做試驗(yàn)時(shí)應(yīng)該更仔細(xì)點(diǎn)。

　　He ought not to have thrown the old clothes away.他不該把舊衣服扔了。(事實(shí)上已扔了。)

　　ought to 在語(yǔ)氣上比should 要強(qiáng)。

　　4) neednt have done sth表示本沒必要做某事，但做了。例如：

　　I dressed very warmly for the trip, but I neednt have done so. The weather was hot.

　　旅行時(shí)，我衣服穿得較多，其實(shí)沒有必要。那時(shí)天很熱。

　　5) would like to have done sth表示本打算做某事，但沒做。例如：

　　I would like to have read the article, but I was very busy then. 我想讀這篇文章，但太忙了一直沒讀。

　　17.8 21.8 should 和ought to

　　除了上述的用法，兩者還可表示想必一定，按理應(yīng)該的意思。例如：

　　I ought to be able to live on my salary. 靠我的薪水，想必也能維持了。

　　It ought to be ready now. 想必現(xiàn)在準(zhǔn)備好了吧。

　　They should be there by now, I think. 現(xiàn)在他們?cè)摰侥莾毫恕?/p>

　　The poems should be out in a month at most. 詩(shī)集估計(jì)最多還有一個(gè)月就要出版了。

　　21.9 had better表示最好，相當(dāng)于一個(gè)助動(dòng)詞，它只有一種形式，它后面要跟動(dòng)詞原形。例如：

　　It is pretty cold. Youd better put on my coat. 天相當(dāng)冷。你最好穿上我的外套。

　　Shed better not play with the dog. 她最好不要玩耍那條狗。

　　had better have done sth表示與事實(shí)相反的結(jié)果，意為本來(lái)最好。例如：

　　You had better have come earlier. 你本該來(lái)得早一點(diǎn)。

　　21.10 would rather表示寧愿

　　would rather do

　　would rather not do

　　would rather than　 寧愿而不愿。

　　還有would sooner, had rather, had sooner都表示寧愿、寧可的意思。例如：

　　If I have a choice, I had sooner not continue my studies at this school. 如果有選擇的余地，我寧可輟學(xué)離開這個(gè)學(xué)校。

　　I would rather stay here than go home. = I would stay here rather than go home. 我寧愿呆在這兒，而不愿回家。

　　典型例題

　　----Shall we go skating or stay at home?

　　----Which ___ do?

　　A. do you rather　　B. would you rather　 C. will you rather　 D. should you rather

　　答案B。本題考查情態(tài)動(dòng)詞rather的用法，would rather +do sth 意為寧愿，本題為疑問(wèn)句，would 提前，所以選B。

　　21.11 will和would

　　注意：1)would like;would like to do = want to 想要，為固定搭配。例如：

　　Would you like to go with me? 想和我一塊去嗎?

　　2)Will you?　Would you like? 表示肯定含義的請(qǐng)求勸說(shuō)時(shí)，疑問(wèn)句中一般用some, 而不是any。例如：

　　Would you like some cake? 吃點(diǎn)蛋糕吧。

　　3)否定結(jié)構(gòu)中用will，一般不用would, wont you是一種委婉語(yǔ)氣。

　　Wont you sit down? 你不坐下嗎?

　　21.12 情態(tài)動(dòng)詞的回答方式

　　問(wèn)句 肯定回答 否定回答

　　Need you? Yes, I must. No, I neednt

　　Must you? No, I dont have to.

　　典型例題

　　1)---Could I borrow your dictionary?

　　---Yes, of course, you____.

　　A. might　B. will　 C. can　 D. should

　　答案C. could表示委婉的語(yǔ)氣，并不為時(shí)態(tài)。答語(yǔ)中of course，表示肯定的語(yǔ)氣，允許某人做某事時(shí)，用can和 may來(lái)表達(dá)，不能用could或might。will 與you連用，用來(lái)提出要求或下命令。should與you 連用，用來(lái)提出勸告。

　　2)---Shall I tell John about it?

　　---No, you ___. Ive told him already.

　　A. neednt　　B. wouldnt　　C. mustnt　　D. shouldnt

　　答案A。neednt 不必，不用。 wouldnt 將不, 不會(huì)的。 mustnt 禁止、不能。 shouldnt　不應(yīng)該。本題為不需要，不必的意思，應(yīng)用neednt。

　　3)---Dont forget to come to my birthday party tomorrow.

　　---______.

　　A. I dont　 B.　I wont　 C. I cant　D. I havent

　　答案B. will既可當(dāng)作情態(tài)動(dòng)詞，表請(qǐng)求、建議、也可作為實(shí)義動(dòng)詞表意愿、意志、決心，本題表示決心，選B。

　　21.13 帶to 的情態(tài)動(dòng)詞

　　帶to 的情態(tài)動(dòng)詞有四個(gè)：ought to, have to, used to, be to, 如加上have got to (=must), be able to，為六個(gè)。它們的疑問(wèn)、否定形式應(yīng)予以注意：

　　Do they have to pay their bill before the end of the month?

　　She didnt use to play tennis before she was fourteen.

　　You ought not to have told her all about it.

　　Ought he to see a heart specialist at once.?

　　ought to 本身作為情態(tài)動(dòng)詞使用。其他的詞作為實(shí)義動(dòng)詞使用，變疑問(wèn)，否定時(shí)，須有do 等助動(dòng)詞協(xié)助。

　　典型例題

　　Tom ought not to ___ me your secret, but he meant no harm.

　　A. have told　B. tell　C. be telling　D. having told

　　答案A。由于后句為過(guò)去時(shí)，告訴秘密的動(dòng)作又發(fā)生在其前因，此地應(yīng)用過(guò)去完成時(shí)，但它在情態(tài)動(dòng)詞 ought to 后，所以用have told。

　　21.14 比較need和dare

　　這兩詞既可做實(shí)義動(dòng)詞用，又可做情態(tài)動(dòng)詞用。作為情態(tài)動(dòng)詞，兩者都只能用于疑問(wèn)句，否定句和條件句。need 作實(shí)義動(dòng)詞時(shí)后面的不定式必須帶to，而dare作實(shí)義動(dòng)詞用時(shí), 后面的to 時(shí)常可以被省略。

　　1) 實(shí)義動(dòng)詞：need(需要, 要求) need + n. / to do sth

　　2) 情態(tài)動(dòng)詞：need，只用原形need后加do，否定形式為need not。例如：

　　Need you go yet? 你要走了嗎?

　　Yes, I must. / No, I neednt.是的，我要走了/不，不急著走。