英語(yǔ)中虛擬語(yǔ)氣的用法很多。在英語(yǔ)教學(xué)的過(guò)程中，我們常常發(fā)現(xiàn)有些學(xué)生對(duì)各種虛擬語(yǔ)氣結(jié)構(gòu)中的動(dòng)詞是用現(xiàn)在虛擬式還是過(guò)去虛擬式分辨不清，下面我就這個(gè)問(wèn)題作一一說(shuō)明?！?BR> 1．表示有可能實(shí)現(xiàn)的意愿的虛擬結(jié)構(gòu)中，動(dòng)詞常用現(xiàn)在虛擬式：
（1）It is + adj + that +Sb + do/be + Sth
該結(jié)構(gòu)中的主語(yǔ)從句表示說(shuō)話人的意愿或主觀態(tài)度，結(jié)構(gòu)中的形容詞用來(lái)表現(xiàn)說(shuō)者的意愿趨向, 從句中的動(dòng)詞應(yīng)用現(xiàn)在虛擬式?？捎糜谠摻Y(jié)構(gòu)中的形容詞包括 advisable, appropriate, crucial, desirable, essential, fitting, imperative（必要的）, important, impossible, natural, necessary, obligatory（必須）, preferable（更好的）, proper, sad, strange, surprising, vital（至關(guān)重要的）等。
如：It is necessary that the car be checked thoroughly.
It was important that she have confidence in herself.
（2） S1 + v + that S2 + do Sth
在帶有賓語(yǔ)從句的英語(yǔ)句子中，如主句中的謂語(yǔ)動(dòng)詞表示以下有可能實(shí)現(xiàn)的意愿時(shí)，從句中的動(dòng)詞應(yīng)用現(xiàn)在虛擬式：
<1> 要求: ask, beg, demand, insist, request, require,
<2> 建議: advise, advocate, propose, recommend, suggest
<3> 命令: command, direct（命令, decree（裁決）instruct, move, order, urge, stipulate。
<4> 愿望: desire, expect, prefer（寧愿）。
<5> 決定：decide。
如：He insisted that you be on time.
It is desired that we get everything ready by tonight.
The commanding officer decided that no one be admitted without a special pass.
（3）N+(…) that +sb +do sth
表示要求、建議、命令、愿望、決定等意義的名詞后如有其同位語(yǔ)從句或表語(yǔ)從句時(shí)，這類從句中的動(dòng)詞應(yīng)用現(xiàn)在虛擬式。適用于該句型的名詞有advice, conviction, decision, decree, demand, idea, motion, necessity, order, plan, preference, proposal, recommendation, requirement, resolution (決議), suggestion, wish。
如：My idea is that we go right now.
The resolution that women be allowed to vote was carried.
（4）Fear/be afraid/worried lest Sb do Sth 表示害怕(擔(dān)心)某種可能出現(xiàn)的情況，從句中的動(dòng)詞應(yīng)用現(xiàn)在虛擬式。
如: I fear lest he arrive too late.
We were afraid lest it be stolen.
He was at once worried lest she leave him.
2．在用來(lái)表示不太可能實(shí)現(xiàn)的意愿或假設(shè)的虛擬結(jié)構(gòu)中，動(dòng)詞常用過(guò)去虛擬式：
（1）Would that sb did sth/ had done sth
該結(jié)構(gòu)表示與現(xiàn)實(shí)相反的愿望（would充當(dāng)及物動(dòng)詞），that從句中的動(dòng)詞應(yīng)用過(guò)去虛擬式。
如：Would that I were a student again.
Would that you didn't refuse my proposal of marriage（求婚）.
Would that I had told him the change last Friday.
（2）If only
If only有兩種主要用法:
① 表示目前較難實(shí)現(xiàn)的愿望或與過(guò)去事實(shí)相反的愿望。表示目前較難實(shí)現(xiàn)的愿望時(shí)使
If only Sb+ did/were Sth 或 if only Sb could/would do/be Sth的結(jié)構(gòu)；表示與過(guò)去事實(shí)相反的愿望時(shí)使用if only Sb had done/been Sth 或 if only Sb could have done Sth的結(jié)構(gòu)。
如：Oh, if he could only come
If only you would listen to reason.
If only I could have gone to the movies.
If only you hadn't told Linda what I said.
② if only 還可帶一個(gè)條件狀語(yǔ)從句，該條件句表示一種較難兌現(xiàn)的條件。
如：If only you would help me type my paper this afternoon, I would not have to burn the midnight oil.
If only they were here now, we would be able to discuss the issue together.
（3）But for和Except for（若非）
but for 和except for均需置于句首，其后均可接名詞短語(yǔ)，表示與事實(shí)相反的假設(shè)或條件，其后句子中的謂語(yǔ)要用should/would/could (not)do/be…來(lái)表示對(duì)現(xiàn)在的虛擬；而用should/would (not) have done/been… 來(lái)表示對(duì)過(guò)去的虛擬。
如：But/Except for air and water, nothing could live in the earth.
But/Except for the storm, I could have swam across the Channel.
But/Except for Martin's arms, I would have collapsed.
(4) but that（若非）
But that 后接真實(shí)情況的條件從句，該從句不用虛擬式，可置于句首或句中，而主句則需用 虛擬式Sb would (not) have done Sth（對(duì)過(guò)去）。
如：But that he was prevented, he would have shot the other gay.
He would have said no but that he was afraid.
（5）If引導(dǎo)的非真實(shí)條件句
在If 引導(dǎo)的非真實(shí)條件句中，if Sb did/were sth表示對(duì)現(xiàn)在或?qū)?lái)的虛擬，這時(shí)主句用would do sth/would be doing sth來(lái)表示現(xiàn)在或?qū)?lái)難以實(shí)現(xiàn)的愿望或假設(shè)；if Sb had done/been sth表示對(duì)過(guò)去的虛擬，這時(shí)主句用could/might/should/would have done/been sth來(lái)表示過(guò)去未能實(shí)現(xiàn)的愿望或假設(shè)。如果省去條件句中的if，則引起該條件句的倒裝。
如：If I were you, I'd marry her.
If we were men, we'd be doing something decent now.
Had he come earlier, he would have met her.
I should have talked to mother if I had thought of it.
（6）if it were not / had not been for…
該結(jié)構(gòu)也是由if引導(dǎo)的非真實(shí)條件句，其中if it were not for…是與現(xiàn)在事實(shí)相反的條件句（句中的were不可替換成was），意為"要不是…"，這時(shí)主句中的動(dòng)詞使用過(guò)去將來(lái)式；if it had not been for…是與過(guò)去事實(shí)相反的條件句，這時(shí)主句中的動(dòng)詞使用過(guò)去將來(lái)完成式（另外，該條件句中的if如被省去時(shí)則引起倒裝）。
例如：If it had not been for the newspaper, I would never have found my lost daughter.
Were it not for the sun, there would be no plant on our planet.
（7）Sb wish后的賓語(yǔ)從句
Sb wish后的賓語(yǔ)從句要用虛擬語(yǔ)氣，表示與實(shí)際情況相反的愿望，其中對(duì)過(guò)去的虛擬要用Sb wish that Sb/sth had done或could/ might/would have done sth；對(duì)現(xiàn)在的虛擬要用Sb wish that Sb/sth were/did sth；對(duì)將來(lái)的虛擬要用Sb wish that Sb/sth could/might/would do sth。
如：I wish I had bought the house.
I wish you could have passed the test.
He wishes he were my age.
We wish you would try again.
（8）As if/though + Sb (or sth did/were 或 as if/though + Sb (or sth) had done/been
該結(jié)構(gòu)表示非真實(shí)的想法或比喻, 結(jié)構(gòu)中的動(dòng)詞用過(guò)去虛擬式。
如:You look as if you'd seen a ghost.
Why is she looking at me as though she knew me? I've never seen her before in my life.
（9）It is (high/about) time that sb + did/were Sth.
該結(jié)構(gòu)表示"到了非要做某事的時(shí)候了（早該做某事了），現(xiàn)在已錯(cuò)過(guò)了做某事的時(shí)機(jī)了"從句中的動(dòng)詞要用過(guò)去虛擬式。
如：It's about time you wrote your homework.
It is high time that you went to bed.
注意：該結(jié)構(gòu)從句中的動(dòng)詞如果是be動(dòng)詞的話，接在第一、三人稱單數(shù)的主語(yǔ)之后時(shí)應(yīng)該用was而不用were，
如：It is high time that I was in bed.
（1）It is + adj + that +Sb + do/be + Sth
該結(jié)構(gòu)中的主語(yǔ)從句表示說(shuō)話人的意愿或主觀態(tài)度，結(jié)構(gòu)中的形容詞用來(lái)表現(xiàn)說(shuō)者的意愿趨向, 從句中的動(dòng)詞應(yīng)用現(xiàn)在虛擬式?？捎糜谠摻Y(jié)構(gòu)中的形容詞包括 advisable, appropriate, crucial, desirable, essential, fitting, imperative（必要的）, important, impossible, natural, necessary, obligatory（必須）, preferable（更好的）, proper, sad, strange, surprising, vital（至關(guān)重要的）等。
如：It is necessary that the car be checked thoroughly.
It was important that she have confidence in herself.
（2） S1 + v + that S2 + do Sth
在帶有賓語(yǔ)從句的英語(yǔ)句子中，如主句中的謂語(yǔ)動(dòng)詞表示以下有可能實(shí)現(xiàn)的意愿時(shí)，從句中的動(dòng)詞應(yīng)用現(xiàn)在虛擬式：
<1> 要求: ask, beg, demand, insist, request, require,
<2> 建議: advise, advocate, propose, recommend, suggest
<3> 命令: command, direct（命令, decree（裁決）instruct, move, order, urge, stipulate。
<4> 愿望: desire, expect, prefer（寧愿）。
<5> 決定：decide。
如：He insisted that you be on time.
It is desired that we get everything ready by tonight.
The commanding officer decided that no one be admitted without a special pass.
（3）N+(…) that +sb +do sth
表示要求、建議、命令、愿望、決定等意義的名詞后如有其同位語(yǔ)從句或表語(yǔ)從句時(shí)，這類從句中的動(dòng)詞應(yīng)用現(xiàn)在虛擬式。適用于該句型的名詞有advice, conviction, decision, decree, demand, idea, motion, necessity, order, plan, preference, proposal, recommendation, requirement, resolution (決議), suggestion, wish。
如：My idea is that we go right now.
The resolution that women be allowed to vote was carried.
（4）Fear/be afraid/worried lest Sb do Sth 表示害怕(擔(dān)心)某種可能出現(xiàn)的情況，從句中的動(dòng)詞應(yīng)用現(xiàn)在虛擬式。
如: I fear lest he arrive too late.
We were afraid lest it be stolen.
He was at once worried lest she leave him.
2．在用來(lái)表示不太可能實(shí)現(xiàn)的意愿或假設(shè)的虛擬結(jié)構(gòu)中，動(dòng)詞常用過(guò)去虛擬式：
（1）Would that sb did sth/ had done sth
該結(jié)構(gòu)表示與現(xiàn)實(shí)相反的愿望（would充當(dāng)及物動(dòng)詞），that從句中的動(dòng)詞應(yīng)用過(guò)去虛擬式。
如：Would that I were a student again.
Would that you didn't refuse my proposal of marriage（求婚）.
Would that I had told him the change last Friday.
（2）If only
If only有兩種主要用法:
① 表示目前較難實(shí)現(xiàn)的愿望或與過(guò)去事實(shí)相反的愿望。表示目前較難實(shí)現(xiàn)的愿望時(shí)使
If only Sb+ did/were Sth 或 if only Sb could/would do/be Sth的結(jié)構(gòu)；表示與過(guò)去事實(shí)相反的愿望時(shí)使用if only Sb had done/been Sth 或 if only Sb could have done Sth的結(jié)構(gòu)。
如：Oh, if he could only come
If only you would listen to reason.
If only I could have gone to the movies.
If only you hadn't told Linda what I said.
② if only 還可帶一個(gè)條件狀語(yǔ)從句，該條件句表示一種較難兌現(xiàn)的條件。
如：If only you would help me type my paper this afternoon, I would not have to burn the midnight oil.
If only they were here now, we would be able to discuss the issue together.
（3）But for和Except for（若非）
but for 和except for均需置于句首，其后均可接名詞短語(yǔ)，表示與事實(shí)相反的假設(shè)或條件，其后句子中的謂語(yǔ)要用should/would/could (not)do/be…來(lái)表示對(duì)現(xiàn)在的虛擬；而用should/would (not) have done/been… 來(lái)表示對(duì)過(guò)去的虛擬。
如：But/Except for air and water, nothing could live in the earth.
But/Except for the storm, I could have swam across the Channel.
But/Except for Martin's arms, I would have collapsed.
(4) but that（若非）
But that 后接真實(shí)情況的條件從句，該從句不用虛擬式，可置于句首或句中，而主句則需用 虛擬式Sb would (not) have done Sth（對(duì)過(guò)去）。
如：But that he was prevented, he would have shot the other gay.
He would have said no but that he was afraid.
（5）If引導(dǎo)的非真實(shí)條件句
在If 引導(dǎo)的非真實(shí)條件句中，if Sb did/were sth表示對(duì)現(xiàn)在或?qū)?lái)的虛擬，這時(shí)主句用would do sth/would be doing sth來(lái)表示現(xiàn)在或?qū)?lái)難以實(shí)現(xiàn)的愿望或假設(shè)；if Sb had done/been sth表示對(duì)過(guò)去的虛擬，這時(shí)主句用could/might/should/would have done/been sth來(lái)表示過(guò)去未能實(shí)現(xiàn)的愿望或假設(shè)。如果省去條件句中的if，則引起該條件句的倒裝。
如：If I were you, I'd marry her.
If we were men, we'd be doing something decent now.
Had he come earlier, he would have met her.
I should have talked to mother if I had thought of it.
（6）if it were not / had not been for…
該結(jié)構(gòu)也是由if引導(dǎo)的非真實(shí)條件句，其中if it were not for…是與現(xiàn)在事實(shí)相反的條件句（句中的were不可替換成was），意為"要不是…"，這時(shí)主句中的動(dòng)詞使用過(guò)去將來(lái)式；if it had not been for…是與過(guò)去事實(shí)相反的條件句，這時(shí)主句中的動(dòng)詞使用過(guò)去將來(lái)完成式（另外，該條件句中的if如被省去時(shí)則引起倒裝）。
例如：If it had not been for the newspaper, I would never have found my lost daughter.
Were it not for the sun, there would be no plant on our planet.
（7）Sb wish后的賓語(yǔ)從句
Sb wish后的賓語(yǔ)從句要用虛擬語(yǔ)氣，表示與實(shí)際情況相反的愿望，其中對(duì)過(guò)去的虛擬要用Sb wish that Sb/sth had done或could/ might/would have done sth；對(duì)現(xiàn)在的虛擬要用Sb wish that Sb/sth were/did sth；對(duì)將來(lái)的虛擬要用Sb wish that Sb/sth could/might/would do sth。
如：I wish I had bought the house.
I wish you could have passed the test.
He wishes he were my age.
We wish you would try again.
（8）As if/though + Sb (or sth did/were 或 as if/though + Sb (or sth) had done/been
該結(jié)構(gòu)表示非真實(shí)的想法或比喻, 結(jié)構(gòu)中的動(dòng)詞用過(guò)去虛擬式。
如:You look as if you'd seen a ghost.
Why is she looking at me as though she knew me? I've never seen her before in my life.
（9）It is (high/about) time that sb + did/were Sth.
該結(jié)構(gòu)表示"到了非要做某事的時(shí)候了（早該做某事了），現(xiàn)在已錯(cuò)過(guò)了做某事的時(shí)機(jī)了"從句中的動(dòng)詞要用過(guò)去虛擬式。
如：It's about time you wrote your homework.
It is high time that you went to bed.
注意：該結(jié)構(gòu)從句中的動(dòng)詞如果是be動(dòng)詞的話，接在第一、三人稱單數(shù)的主語(yǔ)之后時(shí)應(yīng)該用was而不用were，
如：It is high time that I was in bed.