表示与现在或将来事实相反： 条件从句：If + 主语（I，we。。。）+ 动词过去式（v-ed）(be动词一律使用were)
结果主句：主语（I，we。。。）+ should / would。。。+动词原形（V。）
e.g. (1)If I were you, I should go and see the doctor at once.(表示与现在事实相反)
(2)If it were Sunday tomorrow, I would go to see my friends.（表示与将来事实相反） 2. 虚拟语气在条件句中表示与过去事实相反： 条件从句：If + 主语（I, we…）+ had +过去分词（p.p.） 结果主句：主语(I, we…) + should / would / … + have + 过去分词 （p.p.）
e.g. If you had come a
few minutes earlier, you would have met him.
3. 省略了条件从句的虚拟语气（将条件从句转换为介词短语的虚拟语气） e.g. （1）Book1: Unit4 : para. 2; S3:
Without the distraction of TV, they might sit around together after dinner and actually talk to one another.
Without the distraction of TV = If they had no distraction of TV.
(2)Without water, no fish could live.
Without water = If we had no water.
4. 在动词suggest, order, demand, propose, command, request, desire, insist…(这类表示主观想象、意愿，而非客观事实的动词之后的宾语从句里要求
