由下列名词或短语引导，或含有某些词的从句中应用的虚拟语气

1.“Iest 以免、惟恐”引导的从句用“should+动词原形”。

He took a map with him lest he (should ) lose his wag there.

2.“whether不管、无论”引导的让步状语从句，有时用动词原形。

All things, whether you know or don’ t know, exist in the world.

3.用“would rather/had rather’ would just as soon"表示“宁愿、但愿”，后面的宾语从句谓语用过去式或动词原形表示对将来的要求，用过去时表示对现在的愿望，用过去完成时表示对过去做的事的懊悔。

Don’ t live in the world, I would rather( I would just as soon) you die.

I would rather you go tomorrow.

I would rather everything hadn’ t happened in the past.

4.用“had hoped”表示原来希望做到而实际上未能实现的事情，其宾语从句的谓语用“would+动词原形”。

I had hoped that she would go to the U.S. and study there, but she said she liked to stay in China.

5.在“It is(high/about)time+that”引导的定语从句中，定语从句的主谓语用一般过去时，偶尔也可以用would(或should)+动词原形，或had rather (would rather)+动词原形。

It is hihg (about)time that we left/should leave/ had better leave/had rather leave/ were leaving.(注意与“This is the first/second…time”后从句中用现在完成时的区别。

6.用“without/but for/in the absence of ”表示“要不是”，“如果没有”(相当于if it were not for…)表示条件时，句中一般用虚拟语气。(也可用陈述语气)

Without your help, I couldn’ t finish my work on time.

In the absence of water and air, nothing could live.

7.由“providing (that)/ provided (that)/on condition that/ in order that”引导的条件从句或目的从句，根据情况，可用虚拟语气。(有时也可用陈述语气)

They are willing surrender provided they are given free passage. if ,将were等提到主语前，形成倒装。

Should there be a good film tomorrow. I would go to the theatre with you.

Were it not for your help. I wouldn’ t be succeed.