虚   拟   语   气

英语动词有四种语气：陈述语气、祈使语气、疑问语气和虚拟语气。
一．定义：虚拟语气是一种动词形式，表示说话人的一种愿望，假设，怀疑，猜测，建议等含义。虚拟语气所表示的含义不是客观存在的事实。

二．虚拟语气在非真实条件句中
1.概念
           真实条件句：表示现实或可能变为现实的条件。
           非真实条件句：表示非现实的，或不可能，或不大可能变为现实的条件。
  e.g. ①They don’t have a meeting if there is nothing to discuss.
      ②If I had time,I would study German.

2.形式
     虚 拟 条 件 句       主       句
 与现在事实相反 动词过去式（be动词用were） should/would/could/might+do
 与过去事实相反 had+done should/would/could/might+have+done
 与将来事实相反 ①动词过去式
②should+do
③were to+do
should/would/could/might+do

e.g. ①If you had got up earlier,you could have caught the train.
②If he came tomorrow,we could ask him.

练习：
①If you ＿＿＿＿(take) my advice,you ＿＿＿＿＿＿(not fail) in the exams last term.
②If it ＿＿＿＿(rain) tomorrow,the sports meeting ＿＿＿＿＿＿(put off).
③If everyone ＿＿＿＿(know)first aid,many lives ＿＿＿＿＿＿(save).

3.重点
1）如条件句中有were,had,should,可把if省略掉，把were,had,should提前，变为倒装句式。
  e.g. If we had made a great effort,we might have succeeded.→
      Had we made a great effort,we might have succeeded.
▲注意：若条件句的谓语动词是否定形式时，不能用动词的缩略形式。
  e.g. If it weren’t for the expense,I would go abroad now.→
       Were it not for the expense,I would go abroad now.

2)有些句子主句谓语和从句谓语表示的动作在时间上并不一致，这类句子称为“错综时间条件句”。
  ①If you had studied hard before,you would be a college student now.
  ②If he hadn’t followed my advice,he wouldn’t do it much better like this.
3）含蓄条件句指句中没有明显的虚拟条件句，而是利用其它手段来暗示存在的虚拟条件，如but for,with,without,otherwise,but等。
  ①But for your help,we couldn’t have finished the work.=
If it had not been for your help,……
  ②I might have given your more help,but I was too busy.
  ③Such a thing wouldn’t have happened elsewhere.
  ④I was ill that day.Otherwise,I would have taken part in the meeting.

4）省去主句的条件句常用if only引导，表示一种不可能实现的愿望。谓语形式：
                             谓语用过去式（与现在事实相反）
                             谓语用had done（与过去事实相反）
                             谓语用could/would/might+do（与将来事实相反）
  e.g. ①If only he were here.
      ②If only the rain would stop.

三．虚拟语气其它用法
1.用于宾语从句中
1）wish后的宾语从句用虚拟语气，表示一种不可能实现的愿望。谓语形式：
过去式（宾语从句动作与wish同时）
had+done(宾语从句动作先于wish)
could/would/might+do（宾语从句动作后于wish）
   e.g. ①I wish (that) I were a flying bird.
       ②I wish (that) I had met that film star yesterday.
       ③I wish he would try again.

2)用于表示建议、命令等词后的宾语从句中，如demand,order,require,insist,suggest,propose,advise等。宾语从句的虚拟语气结构为：(should)+do
   e.g. He ordered that the boy (should) go with him.
▲注意：当suggest作“暗示；表明”讲，insist作“坚持说；坚持认为”讲，宾语从句不用虚拟语气。
  e.g. ①The look on his face suggested that he was angry.
      ②Mike insisted that he had never stolen anything.

3)would rather后的宾语从句用过去式表示与现在或将来事实相反，用过去完成式表示与过去事实相反。
  e.g. ①I’d rather you went home now.
      ②I’d rather you hadn’t made that mistake.

2.用于主语从句中
   It is suggested/proposed/necessary/important/strange/natural/desired+that从句
   It is a pity/a shame/no wonder+that从句
 主语从句的虚拟语气结构为：（should）+do（表达说话者“惊讶、遗憾、应该”等语气）
   e.g. It was a pity that our team should lose the game.
▲注意：以上句式也可用陈述语气。
  e.g. It’s strange that he didn’t come yesterday.

3.用于表语从句和同位语从句中
  在名词advice,order,suggestion,request,proposal,plan,idea等后边that引导的同位语从句，或这些名词作主语时后面that引导的表语从句中，虚拟语气结构为：(should)+do
  e.g. ①We all agreed to his suggestion that we (should) give up the plan.
      ②My idea is that he (should) accept the job.

4.用于定语从句中
 It is (high) time+that从句，从句谓语形式用过去式，或should+do(should不可省略)。
 e.g. It is high time we started (should start) out.

5．as if/as though用在虚拟语气中。
  as if/as though引导表语从句与方式状语从句皆可，谓语形式：
     过去式（从句动作与主句动作同时发生）
     had done（从句动作先于主句动作）
     could/would/might+do（从句动作后于主句动作）
  e.g. ①He looks as if he were a pop star.
      ②They talked about L.A. as if they had been there.

6.“情态动词+have+done”的用法。
1）must have done:“(过去)一定做了…”(否定式为can’t/couldn’t have done)
  e.g. It must have rained last night for the road is quite muddy.

2)can/could have done：“本来能够做…；过去可能会做…”
  e.g. Can he have gone to his uncle’s?

3)can’t/couldn’t have done:“过去不可能做…；过去没能够…”
  e.g. He can’t have forgotten it.

4)may/might have done：“也许已经做…”（只用于肯定句与否定句中，不用于疑问句；否定句中表示“可能不”，用might表示语气更不肯定）
  e.g. He may not have finished the work.

5）should/ought to have done:“本该做…（实际未做）”
  e.g. You ought to have done this exercise more carefully.

6)shouldn’t/ought not to have done:“本不该做…（实际做了）”
  e.g. you shouldn’t have told her the truth.

7)needn’t have done:“本不必做…（实际做了）”
  e.g. You needn’t have taken a taxi here,for it was very near to my house.

8)had better have done:“当时最好做了…”（否定式为had better not have done）
  e.g. You had better not have beaten her.

9)would rather have done：“宁愿当时做了…”（否定式为would rather not have done,两者都有“后悔”之意）
  e.g. I ignored her opinion,but now I would rather not have done that.

10)would like/love to have done sth.“过去愿意做…（实际未做成）”
  e.g. I would love to have gone to the party last night,but I had to work.

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