虛擬語氣
英語有兩種語氣——陳述語氣和虛擬語氣。陳述語氣表示事實上發生的事情或客觀存在的情況。虛擬語氣表示假定、想象、愿望等非事實觀念。
Ⅰ.虛擬語氣在條件句中主要有以下幾種情況。
(1).表達與現在的事實相反的假設或想象：
條件從句 主句
If + 主語 + 過去式， 主語 + should/would + 動詞原形
If + 主語 + were， 主語 + would/should + 動詞原形
(其中，should用于第一人稱，would可用于各個人稱。)
If I had enough money, I should/would buy a camera.
If I were rich, I would help the poor.
(2).表達與過去事實相反的假設或想象：
條件從句 主句
If + 主語 + had + 過去分詞， 主語 + should/would have + 過去分詞
If I had had enough money, I would have bought a car.
�。�= I didn’t have enough money, so I didn’t buy it.）
If it had not rained yesterday, we should have gone fishing.
(3)表達與將來事實相反的假設或想象，有三種形式：
�、贄l件從句 主句
If +主語+ should + 動詞原形， 主語 + should/would + 動詞原形
(表示可能性極小 “萬一”)
If it should rain tomorrow, I would not go.
注意：if從句的動詞形式不分人稱與數，一律用“should+動詞原形”
�、跅l件從句 主句
If +主語 + were to + 動詞原形， 主語 + should/would +動詞原形
If I were to go abroad, I would go to America. 倘若我要出國，我就到美國。
�、蹢l件從句 主句
If +主語 +動詞過去式， 主語 + should/would +動詞原形
If he went to the party, he would be disappointed.
(4) 在條件狀語從句中，常會出現主句所表示的行為所發生的時間與從句表示的行為的時 間不一致，叫做錯綜時間虛擬條件句，即條件從句與主句所指時間不一致。如從句指過去，而主句卻指現在或將來，此時應根據具體的語境，結合上面提到的三種基本類型對時態作出相應的調整。
If you had gone to bed early last night, you would not be so sleepy now.
If I were you, I wouldn’t have gone to the party last night.
(5) 假設情況不用if從句來表示，而是用without, but for, otherwise, or, but等表示一種含蓄條件。
表示與現在或將來相反，用“would (should, could, might)+動詞原形”；表示與過去相反用“would (should, could, might)+have+過去分詞”
I knew my uncle did have no time. Otherwise he would have kept me company to go hiking.
例1：We ______ John's name on the race list yesterday but for his recent injury. (2011·江西卷28)
A. will put B. will have put C. would put D. would have put
例2: I ______ through that bitter period without your generous help. (2011·陜西卷22)
A. couldn't have gone B. didn't go
C. wouldn't go D. hadn't gone
(5)條件從句if的省略：
當從句中有were，過去分詞had, 或should時，if經常省略。此時，主語后面的主動詞（were， had，should等）被移至句首。
Were I a bird, I would fly to you.
= If I were a bird, I would fly to you,
Should it rain tomorrow, I would not go there.
= If it should rain tomorrow, I would not go there.
例:______ in your position, I would go.
A. If I B. Were I C. If was I D. If I am
Ⅱ用在從句中的虛擬語氣
⒈賓語從句中的應用
（1） wish后的賓語從句：
表示與現在事實相反的愿望，從句謂語用一般過去時或過去進行時；
表示與過去相反的愿望，從句謂語用過去完成時；
表示將來沒有把握或不太可能實現的主觀愿望，常用“would (could)+動詞原形”。
I wish I knew the answer to the question..
I wished I hadn’t spent so much money.
I wish it would stop raining.
I wish you would come soon.
例：— Where are the children?
— I wish they ______ always late. (2011·北京卷28)
A. weren't B. hadn't been
C. wouldn't be D. wouldn't have been
(2) 在具有愿望、請求、建議、命令等主觀意愿的動詞(desire, demand, advice, insist, require, suggest, propose, order, recommend, decide …) 后的賓語從句中需用虛擬語氣。謂語動詞用(should) +動詞原形。值得注意的是，如果賓語從句的動詞是否定的，否定詞not的位置應在動詞之前，而不是動詞之后。
I demand that he (should) answer me immediately.
The head nurse insisted that the patient not be move.
【注意】
(1)suggest 意為“表明，暗示”時，賓語從句不用虛擬語氣.
His pale face suggested that he was in poor health.
(2)insist 意為“堅持認為，堅持說”時，賓語從句不用虛擬語氣。
He insisted that he did not kill the boy.
2. 主語從句中的應用
It is+形容詞/ 名詞/ 過去分詞+ that引導的主語從句，主語從句中謂語動詞常用 “should + 動詞原形”。
常用形容詞有：necessary, important, essential, imperative, urgent, preferable, vital, advisable等
常用名詞有：duty, pity, regret, no wonder, shame等。
常用過去分詞有：demanded, suggested, required, requested, ordered, decided等
It is suggested that pupils (should) wear school uniforms.
It is important that everyone (should) inform themselves of these rules.
It is a pity that he (should) refuse to accept the offer
3.表語從句中的應用
上述動詞相應的名詞形式作主語+連系動詞構成表語從句，要用虛擬語氣，即“should + 動詞原形”.常用名詞形式有：advice, decision, demand, proposal, request, order, suggestion等。
His suggestion was that the meeting (should) be put off.
Ⅲ其他形式的虛擬語氣
1. 在It's (high/about) time “該干某事了” 之后的定語從句中需用虛擬語氣。謂語動詞用過去式.
It is high time that you went to school.
2. 虛擬語氣在as if / as though 引導的方式狀語從句中的應用（謂語動詞形式與wish后的賓語從句基本相同）
表示與現在事實相反，從句謂語用一般過去時或過去進行時；
表示與過去事實相反，用過去完成時；
表示將來的可能性不大，用“would (could)+動詞原形”
He felt as if he were responsible for what had happened.
He treats me as if I were a stranger.
Even if she had been ill, she would have gone to her office.
3.if only 引起的感嘆句中需用虛擬語氣
表示與現在或未來事情相反的愿望，謂語動詞用 過去式 或 would/should+動詞原形
表示與過去事實相反的愿望，謂語動詞用 過去完成式。
Look at the terrible situation I am in! If only I had followed your advice.
If only I had not been busy last week.
4. would （had）rather , would sooner也用來表達主觀愿望，它們之后的賓語從句中需用虛擬語氣。
表示與現在或未來事情相反的愿望，謂語動詞用 過去式.
表示與過去事實相反的愿望，謂語動詞用 過去完成式.
I would rather he went right now.
補充：“情態動詞+have done”的用法
must have done表示對過去事情的肯定推測。
can't / couldn't have done表示對過去所發生的事情所做的否定推測。
may have done表示過去所發生的事情作可能性推測。
might / could have done表示對過去所發生的事情作可能性推測，或者表示本來可以做而事實上未做的事情。
should / ought to have done表示本應該做的事情而事實上未做，含有對對方的責備。
needn't have done表示做了本不應該做的事情。
例1：They ______ have arrived at lunchtime but their flight was delayed. (2011·新課標卷32)
A. will B. can
C. must D. should
例2：— I left my handbag on the train, but luckily someone gave it to a railway official.
— How unbelievable to get it back! I mean, someone ______ it. (2011·江蘇卷34)
A. will have stolen B. might have stolen
C. should have stolen D. must have stolen
語法專項練習：
1. But for the help of John, he _____ last night.
A. should have drowned B. would have drowned
C. was drowned D. may have drowned
2. If it _____ fine tomorrow, we would go for a swim in the sea.
A. would be B. should be C. is D. was to
3. He suffered a sudden heart attack and her wife found him dead when she got home from work. But _____.
A. if his wife came back earlier, he might be saved
B. if his wife had come back earlier, he might be saved
C. if his wife came back earlier, he might have been saved
D. if his wife had come back earlier, he might have been saved
4. I would rather she _____ tomorrow than by plane.
A. travel on train B. traveled by train
C. travels by train D. travelling by the train
5. How old would you _____ if you _____ in 1900?
A. be; had been born B. be; would be born
C. have been; would be born D. have been; were
6. _____ the sun, nothing on earth could live.
A. Were it not to B. If it were not to
C. If it had not been for D. If it were not for
7. If he _____, give him the message.
A. were coming B. would come C. should come D. were come
8. Were I to move to a foreign country, I _____ away all my furniture in my house here.
A. would give B. shall give
C. gave D. will give
9. I would go to the concert but I _____ no time.
A. had B. had had C. have D. has
10. —Would you have told him the answer?
—Yes, I would have, but I _____ so busy then.
A. had been B. were C. was D. am
11. —Why didn’t you buy it?
—I _____ but I didn’t have the money.
A. would B. would have
C. had had D. had bought
12. —You should have finished it sooner.
—I know but I _____ the time.
A. don’t have B. won’t have C. didn’t have D. had not
13. _____ water, we could not live a day in the desert.
A. Without B. No C. Having no D. But not for
14. If you _____ the doctor’s advice, you would have recovered already.
A. followed B. would followed C. will follow D. had followed
15. If he had not lost the money, he _____ the piano last week.
A. could have bought B. had bought
C. would buy D. have bought
答案與解析：
1. 選B。but for表示“如果不是……的話”，與虛擬語氣搭配使用。
2. 選B。表示與將來事實相反的虛擬語氣，從句用should do或者were to do.
3. 選D。表示與過去事實相反的虛擬語氣。
4. 選B。would rather后面的賓語從句用虛擬語氣，形式是：would rather sb. did/had done.
5. 選A。從句與過去事實相反，而主句與現在事實相反。
6. 選D。表示與現在事實相反的虛擬語氣，意思是“如果不是有太陽的話”。
7. 選C。表示與將來事實相反的虛擬語氣，從句用should do.
8. 選A。表示與將來事實相反的虛擬語氣，主句用would/should do.
9. 選C。but后面的分句表示事實情況，不用虛擬語氣。
10. 選C。but后面的分句表示過去的事實情況，因此用過去時。
11. 選B。虛擬語氣和事實情況混合的用法，第一個分句是虛擬，而but后面是事實情況。
12. 選C。but后面的分句表示過去的事實情況，因此用過去時。
13. 選A。without經常代替虛擬的從句，表示假設。
14. 選D。表示與過去事實相反的虛擬語氣，從句用過去完成時。
15. 選A。could have done表示“本來可以做某事”。
編輯者：攀枝花家教網（www.toutou518.com)