虛擬語氣是英語中常出現的一種語言現象，近幾年成了高考語法題中的一個熱點。每年都有不少省份高考試題中考到這一考點。對於許多中國學生來說，它也是一個難點。無怪乎許多學生學完虛擬語氣後，常常會嘆道：If there were no subjunctive mood（虛擬語氣）, English ______ much easier.A. will be B. would have been C. could have been D. would be這就是個有關虛擬語氣的題目，本題答案選什麼呢？本文要來解答這個問題。讓我們來看看虛擬語氣有哪些常見的重要考點
考點一 非真實條件句中的虛擬語氣
考例1.If he______ my advice, he wouldn't have lost his job.
A. followed B. should follow C. had followed D. would follow
【分析】C。本題考查的是與過去事實相反的非真實條件句中虛擬語氣的用法。根據主句中的時態為過去將來完成時，那麼對應的條件句中就應該使用過去完成時，所以答案為C。
【方法技巧】在含有if非真實條件句的虛擬語氣中，if從句與主句的謂語動詞變化規則是：
如何輕鬆記住這些規則並運用自如呢？大家可記這個口訣。即「現/過/過將，過/過完/過將完，將/過/過將。」「現」即虛擬與現在事實相反的情況，「過」則表示if從句中的謂語動詞用過去時（動詞過去式），「過將」則表示主句謂語動詞使用過去將來時（would do）；「過過完過將完」則表示虛擬與過去事實相反的情況時，if 從句中的謂語動詞用過去完成時（had done），主句中的謂語動詞用過去將來完成時（would have done）；「將過將過將」則表示虛擬與將來事實相反的情況時，if從句中的謂語動詞使用過去式［註：另外的兩種形式should do或were to do亦可］，主句中的謂語動詞也使用過去將來時（would do）。
那麼，在本文前面提到的那個題目應該選什麼呢？這是與現在事實相反的虛擬語氣，條件句是過去時，對應的口訣是現/過/過將，應使用過去將來時，我們可知答案為D。
考例2. This printer is of good quality. If it _______ break down within the first year, we would repair it at our expense.
A. would B. should C. could D. might
【分析】B。本題考查的是與將來事實相反的非真實條件狀語從句中虛擬語氣的用法。根據上面的表格以及變化口訣可知，本題中主句為過去將來時，if從句對應的時態應該使用過去時或were to+動詞原形或should+動詞原形，故答案只能選B。
考例3. I am not free today. If I _____free today, I _____ and visit some of my friends.
A. am, will go B. were, would go C. were, shall be D. be, must go
【分析】B。根據句中的關鍵詞today可知，本題考查的是與現在事實相反的虛擬語氣的用法。根據上面的表格以及變化口訣可知，本題中if從句對應的應該使用過去時，主句為過去將來時，故答案只能是選B。
考點二 錯綜時間虛擬條件句
考例4. Maybe if I _____ science, and not literature then, I would be able to give you more help.
A. studied B. would study C. had studied D. was studying
【分析】C。本題中主句和從句與不同時間的事實相反。主句用的過去將來時，說明是與現在事實相反，但從句中有一個過去時間then，根據上下文來看，從句是與過去事實相反，所以應該使用對應的過去完成時。所以答案為Ｃ。
【方法技巧】當從句與主句或上下文所表述的時間不一致時，我們切不可照搬某種形式，而應該按照句中所表述的時間關係，再選擇相應的虛擬形式。再如：
If you had worked hard yesterday, you would be tired now.（注意主句與從句的不同時間）
考例5. I ______ sooner but I didn’t know that they were waiting for me.
A. had come B. was coming C. would come D. would have come
【分析】Ｄ。根據but後面句子的意思可知這是一個過去的客觀事實，那麼前句就是一個與過去事實相反的主句了,所以要使用過去將來完成時。本句可以理解為If I had known that they were waiting for me, I would have com sooner. But I didn’t know that they were waiting for me.
考點三 省略if情況
考例6. Had I known about this computer program, a huge amount of time and energy_________ .
A. would have been saved B. had been saved
C. will be saved D. was saved
【分析】A。本題中的前面句子是一個省略if後再把had提前的從句。根據從句中使用的是過去完成時，說明是一個與過去事實相反的虛擬語氣，那麼主句中就對應使用過去將來完成時。所以答案選Ａ。
【方法技巧】若虛擬條件句中有 were, had, should 時，可省略 if 而將 were, had, should 移到句首。
考點四 名詞性從句中的虛擬語氣
1）賓語從句中的虛擬語氣
考例7. Teachers recommend parents_______their children under 12 to ride bicycles to school for safety.
A. not allow B. do not allow C. mustn’t allow D. couldn’t allow
【分析】Ａ。本題中的關鍵詞是recommend是「推薦；建議」的意思，在後面接賓語從句時應該使用should+do，其中should可以省略。故答案為Ａ。
【方法技巧】在某些動詞後的賓語從句中需用should+動詞原形的虛擬語氣形式。「should」可以省略。常見的動詞有：一個堅持insist；兩個命令order， command ； 三條建議suggest， advise， propose； 六項要求demand， request， require， ask， urge， desire。注意：suggest表「暗示，表明」時， insist表「堅持認為」時不用虛擬語氣。
2）主語從句中的虛擬語氣
考例8. _____ in the regulations that you should not tell other people the password of your e-mail account.
A. What is required B. What requires C. It is required D. It requires
【分析】C。本題考查的是主語從句中含有required（要求）的虛擬語氣的用法，從句中也要使用should+do，其中should可以省略。
【方法技巧】主語從句中的虛擬語氣基本句型有：1. It be+過去分詞+that…+(should)+動詞原形+…過去分詞：suggested, requested, ordered, proposed, demanded, arranged, desired, advised如：It’s suggested that everybody (should) buy a dictionary.2. It be+形容詞+that…+(should)+動詞原形+…形容詞:important, necessary, natural, right, wrong, better, proper, funny, strange, surprising…如：It is necessary that we (should ) have a walk now.3. It be+名詞（ a pity/a shame/ no wonder） that… + (should)+動詞原形+…如：It seems such a pity that you should have to spend the day at the hotel.
3）表語從句、同位語從句中的虛擬語氣
考例9. His suggestion that you _____ once more sounds reasonable.
A. try B. tries C. must try D. can try
【分析】A。本題考查的是同位語從句中的虛擬語氣的用法。因句中也含有suggestion（建議），從句中要使用should+do，其中should可以省略。
【方法技巧】某些表示「建議、請求、命令」等意義的名詞後的表語從句或同位語從句需用「（should）＋動詞原形」構成謂語。這類名詞有：advice，desire，decision， idea，order，plan，proposal，recommendation，request，suggestion等，如：His recommendation is that we（should）go there by train．
考點五 幾種特殊句式的虛擬語氣:
1）would rather+從句
考例10. George is going to talk about the geography of his country, but I』d rather he______ more on its culture. (2010年江蘇)
A. focus B. focused C. would focus D. had focused
【分析】B。本題考查的是would rather後接從句時使用虛擬語氣的用法。從句與現在事實相反時，動詞時態要使用過去時。
【方法技巧】would rather+ 句子(虛擬) 一般過去時 對現在虛擬過去完成時 對過去虛擬一般過去時 對將來虛擬①I would rather you posted the letter right away.②I would rather you had returned the book yesterday.③Don’t come tomorrow. I』d rather you came next weekend.
2）wish+從句
考例11. ----Where are the children? The dinner’s going to be completely ruined. (2011北京)
----I wish they _____ always late.
A. weren’t B. hadn’t been C. wouldn’t be D. wouldn’t have been
【分析】Ａ。本題考查的是wish後接從句時的虛擬語氣用法。題目中是與現在事實相反，所以對應的動詞使用過去時。
【方法技巧】wish 後的賓語從句，若表示不能實現的願望，謂語動詞用過去時表示與現在事實相反的願望；用過去完成時表示與過去事實相反的願望；用「would ／could ／might＋動詞原形」表示與將來可能發生的事情相反的願望。
考點六 句型It is (high, about, low) time that從句
考例12. It’s about time he ______ to do the work.
A. begins B. will begin C. begin D. began
【分析】D。本題考查的是It is (high, about, low) time that從句中的虛擬語氣的用法。從句後面使用過去時或should + do，其中should不能省。
考點七 含蓄式虛擬語氣
考例13. We ______ John’s name on the race list yesterday but for his recent injury.
A. will put B. will have put C. would put D. would have put
【分析】D。本題考查的是含有but for 的含蓄式虛擬語氣的用法。根據題意可知，主句應是與過去事實相反的虛擬語氣，所以對應的要用過去將來完成時。
【方法技巧】1）用介詞短語without，but for （要不是）等表示條件。如：Without air and water (If there were no air and water), all living things on the earth would die．地球上如果沒有空氣和水，一切生物都將死亡。2）用連詞or, otherwise, but, once, though等表示條件。如：He was taken to hospital at once yesterday, otherwise ／ or he would have died already． ＝ If he had not been taken to hospital at once yesterday, he would have died already．昨天他被立即送到了醫院，要不然他早就死了。
3）用分詞短語表示條件。如：
Given more time, we could have done the task much better． ＝ If we had been given more time, we could have done the task much better．如果再給我們點時間，我們會做得更好。
4）if only 若是...那該多好啊; 真希望...; 只要...就好，如：
If only he had lain quietly as the doctor instructed, he would not suffer so much now.