五、虚拟语气
1．与现在事实相反或在可预见的时间段内不可能发生的事情。
2．虚拟句无单数be动词，无现在时态，全部都是相应的过去时态。 虚拟三形式：(would, should, could, might)
现在情况的虚拟：If+主语+一般过去时，主语+would+动词原形
过去情况的虚拟：If+主语+过去完成时，主语+would+have+done 将来情况的虚拟：If+主语+一般过去式，主语+should+动词原形
3．虚拟倒装三形式：省略if，助动词提前。
Were+主语+表语，主语+would+动词原形。
Were I you, I would not come.
Had+主语+过去分词，主语+would+have+done。
Had I come earlier yesterday, I would have met him.
Should+主语+动词原形，主语+would+动词原形。
Should you come, you would come early tomorrow.
4．虚拟特殊形式：
1)wish后that从句用虚拟语气
2)would rather，had rather，would just as soon，had just as soon用did的形式
3)It is (about, high)time that用did的形式
4)以下三类词后的that从句用should+动词原形；需要注意虚拟被动（be done）
动词：demand, request, order, suggest, desire, require, move, propose, advise, recommend, prefer
名词：demand, order, suggestion, desire, requirement, motion, proposal, advice, recommendation
形容词：important, essential, necessary, imperative, advisable, , urgent, desirable, better
5)lest引导的从句用虚拟形式：即should＋动词原形
6)as if、as though和for fear that引导的从句
7)介词but for和without引导的短语
第二篇：虚拟语气总结
l. 时间选择型
当虚拟语气用来表示一种不能成为现实、不真实的情况时，须选择与现在、将来和过去情况相反的三种不同时间，从而决定谓语动词。这类虚拟语气主要用于如下几方面:
（1）虚拟条件句（含蓄虚拟条件句）
If l were you，l would study much harder．（与现在情况相反）
If he did（were to do，should do）it，he would do it well．（与将来情况相反） I wouldn't have finished the work without your help．（与过去情况相反）
（2）由 even if（though）引导的让步状语从句，其谓语动词变化同于虚拟条件句，在口语中也可用直陈语气。
Even if he were here, he wouldn't be able to help you．（与现在情况相反）
Nothing could have saved your father，even if the doctor had arrived on time．（与过去情况相反）
（3） wish后的宾语从句
I wish I were five years younger than you．（与现在情况相反）
He wishes you would go with him.（与将来情况相反）
I wished I had won the match．（与过去情况相反）
注意：wish的时态不影响从句三种时间的判定。
（4） as if（though）引导的表语从句和方式状语从句
He looks as if he were very sleepy．（与现在情况相反）
They are talking about something，as if they were quarrelling with each other．（与现在正发生的惰况相反）
2．should+动词原形型
这种类型的虚拟语气一般用于主语从句、宾语从句、表语和同位语从句。谓语由should+动词原形构成，无论什么人称都不能用 would，should在口语中可以略去。
（1）在主语从句中用以表示惊奇、惋惜、理应如此，构成 It is natural（important, necessary，strange，a pity，a shame等）that… 句型。
It is natural that you should say apology to him．
It is a pity that you should be careless．
（2）用于表示命令、建议一类动词后的宾语从句，如：suggest，move，insist，demand，request，command等。
The young man insisted that he should be sent to do the work．
I suggested that we should set off earlier．
应注意：当insist表示对已发生过的事物的看法，或当suggest为“说明了”，“暗示”的含义时，从句用直陈语气而不用虚拟语气。
The Arab insisted that he hadn't seen the camel．
His smile suggested that he was happy．
（3）当表示间接的要求、建议、命令、决定等名词作主语时，其表语从句用 should+动词原形。这类名词有 suggestion，request，order，advice，idea等。
The officer's order was that his soldiers should repair the defence works at once． His advice is that your father should do more exercises in the morning．
（4）上述名词的同位语从句也应用should+动词原形。
I did not receive the order that you should leave here at once．
His suggest on that you should keep silent is reasonable．
3．一般过去式型
这类虚拟语气的谓语动词一般用动词过去式表示，常用于如下几个方面：
（1）用would，could，might表示说话人的谦逊、客气、婉转。
Could you tell me the way to the cinema？
Would you mind my smoking here？
（2）用于so that和 in order that引导的目的状语从句。
They are climbing higher so that they could see the whole city．
但从句若要否定的话则用shouldn’t。
He locked the door of his room in order that he shouldn't be troubled by someone．
（3）用于It is time that 句型。
It is time that the problem was solved．
在此句型中也可用should+动词原形。应注意该句型若用过去式表示时，第一、三人称单数不可用were代替was。
4．动词原形型
该类型虚拟语气谓语仅用动词原形，第三人称单数也不加“s”
（1）表示强烈愿望。
God save me．
Heaven help us．
（2）用may放在句首表示说话人对对方的祝愿和祝福。
May you be happy．
May you secceed.