虛擬語氣是高考考綱要求掌握的內(nèi)容。高考主要考查虛擬語氣在if引導(dǎo)的非真實(shí)條件句、名詞性從句和其他一些句子中的應(yīng)用。同學(xué)們應(yīng)重點(diǎn)掌握非真實(shí)條件句中的主、從句謂語的對(duì)應(yīng)關(guān)系，牢記哪些詞后的名詞性從句需要使用虛擬語氣。
[虛擬語氣的使用范圍]
虛擬語氣用來表示說話人所說的話并不是事實(shí)，而是一種假設(shè)、愿望、懷疑或推測(cè)，主要用于if條件狀語從句中，也可用于主語從句、表語從句和賓語從句等。
[虛擬語氣用于if條件句]
if條件狀語從句有真實(shí)條件句和非真實(shí)條件句。假設(shè)條件可以實(shí)現(xiàn)的句子是真實(shí)條件句，反之則為非真實(shí)條件句，要用虛擬語氣。其形式分為以下三種：
1. 條件從句與現(xiàn)在事實(shí)不一致，其句型為：if+主語+過去時(shí)，主語+should（could，would，或might）+動(dòng)詞原形。如：
If I were in your position， I would marry her.
2. 條件從句與過去事實(shí)不一致，句型為：if+主語+had+過去分詞，主語+should （could，would，或might）+have+過去分詞。如：
If it had not rained so hard yesterday， we could have played tennis.
3. 條件從句與將來事實(shí)不一致，句型為：if+主語+should/were to（過去時(shí)）+do，主語+should（could ...）+原形do。如：
If you should miss the chance， you would feel sorry for it.
If the sun were to rise in the west， I would lend you the money.
例1 If I it with my own eyes， I wouldn’t have believed it.
A. didn’t see B. weren’t seeing
C. wouldn’t see D. hadn’t seen
解析 D。句意：如果不是親眼看到，我不會(huì)相信。根據(jù)后半句wouldn’t have believed可知是對(duì)過去的虛擬。
4. 省略形式。有時(shí)可以把含有助動(dòng)詞、情態(tài)動(dòng)詞、be動(dòng)詞的虛擬條件句中的連詞if省去，將had，should，were等詞提到主語之前，即用倒裝結(jié)構(gòu)。這時(shí)，如果出現(xiàn)not等否定詞時(shí)需放在主語后面。例如：
Had the doctor come last night， the boy would have saved.
Were I to go to the moon one day， I would see it with my own eyes.
Should it rain tomorrow，we would stay at home.
Had it not been for your help， I wouldn’t have succeeded.
例2 no modern telecommunications， we would have to wait for weeks to get news from around the world.
A. Were there B. Had there been
C. If there are D. If there have been
解析 A。句意：要不是有了現(xiàn)代化的電訊設(shè)備，我們要等幾個(gè)星期才能知道世界各地的新聞。根據(jù)主句的時(shí)態(tài)可知是與現(xiàn)在事實(shí)相反的情況。
5. if only常用來引導(dǎo)省略主句的虛擬條件句。這種條件句常表示不可能實(shí)現(xiàn)的愿望，也用于表示與事實(shí)相反的愿望，虛擬語氣的時(shí)態(tài)與wish后所接時(shí)態(tài)的規(guī)則相同。如：
If only he would find a satisfactory job after his graduation. （與將來事實(shí)相反）
If only my mother had survived the disease. （與過去事實(shí)相反）
If only I were better looking. （與現(xiàn)在事實(shí)相反）
[混合虛擬條件句（錯(cuò)綜虛擬條件句）]
有時(shí)候，條件從句和主句動(dòng)作發(fā)生的時(shí)間是不一致的（如一個(gè)是過去發(fā)生的，一個(gè)是現(xiàn)在發(fā)生的），這時(shí)動(dòng)詞的形式要根據(jù)表示的時(shí)間來調(diào)整。如：
If I had followed the doctor’s advice， I would be better now.
If I were you now， I would have chosen to take a job.
例3 If he had spent more time practicing speaking English before， he able to speak it much better now.
A. will be B. would be
C. has been D. would have been
解析 B。句意：要是他以前多花點(diǎn)時(shí)間練習(xí)英語，他現(xiàn)在就能說得很好了。本題考查混合式虛擬語氣。從句時(shí)間是before，可知與過去事實(shí)相反，用過去完成時(shí)；主句時(shí)間是now，與現(xiàn)在事實(shí)相反。
例4 If it （be） for his invitation the other day， I should not be here now.
解析 had not been。句意：要不是因?yàn)榍皫滋焖难?qǐng)，我現(xiàn)在就不會(huì)在這里了。本題考查混合式虛擬語氣。從句時(shí)間是the other day，表示與過去事實(shí)相反，用過去完成時(shí)；主句時(shí)間now表示與現(xiàn)在事實(shí)相反。
[含蓄虛擬條件句]
有時(shí)一個(gè)假設(shè)的情況并不用條件從句表示，而用其他方式來表示，這樣的句子叫含蓄條件句。主要有以下幾種情況。
1. 用with，without，but for等介詞短語來替代條件從句，它們都可以轉(zhuǎn)換成由if引導(dǎo)的虛擬條件句。如：
Without/But for the sun， nothing would grow.
= If it were not for the sun， nothing would grow.
例5 Without his wartime experiences， Hemingway his famous novel A Farewell to Arms.
A. didn’t write B. hadn’t written
C. wouldn’t write D. wouldn’t have written
解析 D。句意：沒有他的戰(zhàn)時(shí)經(jīng)驗(yàn)，海明威就不可能寫出著名的小說《永別了，武器》。根據(jù)without his wartime experience（沒有戰(zhàn)時(shí)的經(jīng)歷），可知這里表示與過去事實(shí)相反的猜測(cè)，故主句用would have done。
2. 用or，otherwise，but等引導(dǎo)的虛擬語氣。如：
You didn’t come yesterday，or you would have seen him.
I was very busy last week，otherwise I would have come to see you.
例6 It is lucky we booked a room，or we ， nowhere to stay now.
A. had B. had had
C. would have D. would have had
解析 C。句意：我們很幸運(yùn)地訂到了房間，否則，我們現(xiàn)在就會(huì)無處可去了。or引導(dǎo)含蓄虛擬條件句，or后面是主句，相當(dāng)于If we hadn’t booked a room，we would have nowhere to stay now。根據(jù)“now”可知是對(duì)現(xiàn)在進(jìn)行虛擬，故選C。
例7 I to my cousin’s birthday party last night， but I was not available
A. went B. had gone
C. would go D. would have gone
解析 D。句意：我原本想去參加表弟昨晚的生日晚會(huì)，但是我沒有時(shí)間。根據(jù)后半句but I was ...可知真實(shí)時(shí)態(tài)是一般過去時(shí)，與過去事實(shí)相反，前半句相當(dāng)于If I had had time，I would have gone to ...。
[as if/though引導(dǎo)的方式狀語從句或表語從句]
1. as if從句用陳述語氣的情況：當(dāng)說話者認(rèn)為句子所述為真實(shí)的或極有可能發(fā)生/存在的事實(shí)時(shí)。如：
It looks as if it is raining.
2. as if 從句用虛擬語氣的情況：當(dāng)說話人認(rèn)為句子所述的是不真實(shí)的或極少有可能發(fā)生/存在的情況時(shí)。從句虛擬語氣動(dòng)詞的時(shí)態(tài)有如下幾種情形：
�。�1）如果從句表示與現(xiàn)在事實(shí)相反，謂語動(dòng)詞用一般過去時(shí)。如：
You look as if you didn’t care.
�。�2）從句表示與過去事實(shí)相反，謂語動(dòng)詞用“had+過去分詞”。如：
He talks about Rome as if he had been there before.
�。�3）從句表示與將來事實(shí)相反，謂語動(dòng)詞用“would/could/might+動(dòng)詞原形”。如：
He opened his mouth as if he would say something.
例8 It was John who broke the window. Why are you talking to me as if I it？
A. had done B. have done
C. did D. am doing
解析 A。句意：是約翰打破了窗戶，為什么你說得像是我做的？從前半句可以看出與過去事實(shí)相反。
[賓語從句中的虛擬語氣]
1、wish后接賓語從句中的虛擬語氣：
主語+wish+（that）+主語+did/were（與現(xiàn)在情況不一致）
主語+wish+（that）+主語+had done（與過去情況不一致）
主語+wish+（that）+主語+would+v.（與將來情況不一致）
如：I wish that I met my uncle now.
I wish I had met my uncle yesterday.
I wish I could meet my uncle tomorrow.
例9 I wish I at my sister’s wedding last Tuesday，but I was on a business trip in New York then.
A. will be B. would be
C. have been D. had been
解析 D。上周二我本希望參加我姐姐的婚禮，但那時(shí)我在紐約出差。本題考查wish引導(dǎo)的賓語從句，表示與過去事實(shí)相反的愿望，用“had+過去分詞”。
2. 表示“要求、建議、命令”等動(dòng)詞后面的賓語從句中的虛擬語氣。從句的謂語動(dòng)詞用“should+動(dòng)詞原形”，其中should可以省略。
當(dāng)insist表示“堅(jiān)持認(rèn)為”，suggest表示“表明，顯示”時(shí)，不用虛擬語氣。如：
Bill insisted that Mike （should） apologize to his father， but Mike insisted that he was right.
His pale look suggested that he was in poor health. So I suggested that he （should） have a good rest at home.
例10 Eye doctors recommend that a child’s first eye exam at the age of six months old.
A. was B. be C. were D. is
解析 B。句意：眼科醫(yī)生建議孩子的視力檢查應(yīng)該在六個(gè)月的時(shí)候進(jìn)行。recommend表示建議，其賓語從句用虛擬語氣should do，should可以省略。
3. would rather后的賓語從句要用虛擬語氣，一般用過去時(shí)態(tài)表示與現(xiàn)在或?qū)硎聦?shí)相反，用過去完成時(shí)表示與過去事實(shí)相反，如：
I would rather you went home now. （與現(xiàn)在事實(shí)相反）
Don’t come tomorrow. I’d rather you came next week. （與將來事實(shí)相反）
I’d rather you hadn’t done that yesterday. （與過去事實(shí)相反）
例11 We would rather our daughter ________ at home with us， but it is her choice， and she is not a child any longer.
A. would stay B. has stayed
C. stayed D. stay
解析 C。句意：我們寧愿我們的女兒和我們住在一起，但是這是她自己的選擇，她已經(jīng)不是一個(gè)孩子了。從后面一句的is可知真實(shí)的時(shí)態(tài)是一般現(xiàn)在時(shí)，would rather后面的賓語從句要用虛擬語氣，表示愿望與現(xiàn)在事實(shí)相反，故答案選C。
[主語從句中的虛擬語氣]
�。�1）It be+形容詞+that ... （should） do ...
It’s necessary/important/strange/surprising/natural ...that ...表達(dá)了說話人的命令、要求、建議或者驚訝，從句中應(yīng)用should+do，其中should可省略。
It’s natural that he （should） feel hurt.
It’s necessary that you （should） work out every day to keep fit.
�。�2）It be+過去分詞+that ... （should） do ...
用于該結(jié)構(gòu)中的過去分詞是表示“建議、請(qǐng)求、命令”等詞的過去分詞，如desired，suggested，requested，ordered，proposed等。
It is desired that the building of the house be completed next month.
�。�3）It is （about/high/quite） time that ...+（過去時(shí)/should+動(dòng)詞原形） ...
It is high time I went/should go home now.
[表語從句、同位語從句中的虛擬語氣]
在suggestion，proposal，order，plan，idea，advice，decision等需要具體內(nèi)容解釋的名詞后要使用虛擬語氣，其謂語動(dòng)詞為：should+do，連接從句的that不能省略。如：
The suggestion that he be invited was rejected. （同位語從句）
That is their demand that their wages be increased. （表語從句）