1、If 条件句
If I were you, I would leave now.
If you had asked me yesterday, I could have told you.
If it should rain tomorrow, we couldnt climb.
NOTICE: 错综时间条件句（根据所表示的时间调整）
If you had followed me, you wouldnt miss the train now.
2、主语从句中的虚拟
①It is (was) important (necessary, strange ) that-clause
Its necessary that you (should) be present at the meeting.
②It is (was) ordered (suggested, required, requested) that-clause
It was ordered that the room (should) be cleaned.
3、wish + that-clause
①现在的愿望：I wish that you werent so lazy.
②过去的愿望：I wish that you hadnt hurt Jim so much.
③将来的愿望：I wish you wouldnt talk like that.
--- Have you ever studied French ?
--- No, but I wish I had.
4、表语从句和同位语从句中的虚拟
通常由几个要求接虚拟语气的名词引起：order, demand, suggestion
He gave orders that the test (should) be finished before 5:30.
His suggestion is that the house (should) be built there.
5、宾语从句中的虚拟
下列动词后的宾语从句用虚拟语气：demand, insist, order, require, etc.
The judge ordered that the thief (should) not be punished.
NOTICE: ①suggest 暗示，表明
Her expression suggested that he was angry.
②insist 坚持认为是怎么回事
The Arab insisted that he had never seen the camel.
He insisted that John (should) do it.
6、状语从句中的虚拟
①as if (though)
与现在相反，从句用过去时
He talks as if he knew everything.
与过去相反，从句用过去完成时
He looks (looked) as if she had wept.
客观事实，从句用陈述句语气
It looks as if you are tired.
②so that, even if (though)
Nothing could have saved him even if he had been tended .
7、由介词短语引起的虚拟语气
①without : Without your help, I shouldnt get a result.
②but for若非： But for you, we couldnt have carried out the plan.
8、句型
①Its time + that-clause (指现在或将来）
Its time that you went to school .( should go to school)
②would rather + that-clause（指现在或将来）
Id rather you went home now.
Dont come tomorrow, Id rather you came next week.
③what if 如果 怎么办?
What if they should come here ?
9、虚拟语气的倒装
Were I you, I would leave now.
Had you asked me yesterday, I could have told you.
Should it rain tomorrow, we couldnt climb.