英语的动词有三种语气形式,即陈述语气、祈使语气和虚拟语气,陈述语气用来说明事实或就事实提出询问,祈使语气用于表示请求、命令、建议或警告等,而虚拟语气则是谓语动词的一种特殊形式,用来表达假设、猜测、可能或空想等虚拟情况,也可以表示主观愿望或表达某种强烈的感情,通常出现在各类从句中。

一. 条件状语从句:

时间

从句谓语形式

主句谓语形式

 

将来

if + 主语+ 动词过去式(be用were)

if+主语+should + 动词原形

if+主语+were to + 动词原形

 

主语+would / should / might / could + 动词原形

现在

if +主语+ 动词一般过去时

主语+ would / should / might / could + 动词原形

过去

if+ 主语+had done

主语+would / should / might / could have + 动词过去分词

例句:

1.现在:

If I were you,I would choose that picture.

2.过去:

If you had taken my advice,you would not have made such a mistake.

3.将来:

If there were a sunny day next Sunday,we would go hiking.

二. 目的状语从句:

1.在for fear that,in case,lest引导的从句中,若用虚拟语气时,从句谓语为:(should) + do。

eg. He started out earlier in case he (should) be late.

2.在so that,in order that所引导的目的状语从句中,从句中的谓语为:can / could / may / might / will / would /should + do。

eg. He goes closer to the speaker so that he can hear him clearer.

三. 原因状语从句:

1. should + 原形动词,表现在或将来

eg. He was angry that you should call him by name.

2. should + 完成式, 表过去

eg. I’m very sorry that you should have failed the test.

四.方式状语从句:

虚拟语气常用于as if, as though 引导的方式状语从句:

时间

结构

主句动作之前

had + 过去分词

主句动作之后

would / could / might / should+动词原形

eg. They began to talk warmly as if they had known each other for long.

They stopped talking as if someone should come.