If真实条件句与虚拟条件句
真实条件句与虚拟条件句
1.真实条件句
真实条件句是指主句中的某一动作或状态是在真实情况下或有可能实现的情形下发生的。

在表示真实条件句的复合句中，表条件的状语从句和表结果的主句的谓语都用陈述语气。

* If you come back late, your mother will worry about you.
如果你回来晚了，你妈妈会担心的。

（if引导真实条件句，主句用一般将来时，从句用一般现在时表将来）
* If your suggestion is rejected, they will let you know.
如果你的建议遭到拒绝，他们会让你知道的。

（if引导真实条件句，主句用一般将来时，从句用一般现在时表将来）
2.虚拟条件句
（1）虚拟条件句指的是与事实相反或不太可能实现的事。

在表示非真实条件的复合句中，表示条件的状语从句和表示结果的主语的谓语动词要用虚拟语气。

* If I were you, I would focus my attention on looking after my elderly parents.
如果我是你，我会把注意力集中在照顾年迈的父母上。

（if引导虚拟条件句，叙述与现在事实相反，主句谓语动词用would do,从句谓语动词用过去式，be用were）
* If he had got up a little earier, he wouldn’t have been late. 如果他早一点起床，他就不会迟到了。

（if引导虚拟条件句，叙述与过去事实相反，主句用谓语动词would have done,从句谓语动词用had done）
* If he should come(were to come/came)tomorrow, I would treat him to dinner.
如果他明天来，我就请他吃饭。

（if引导虚拟条件句，叙述与将来事实相反，主句谓语动词用would do,从句谓语动词有三种形式：should
do, were to do, 过去式）
当条件状语从句表示的动作与主句表示的动作发生的时间不一致时，动词的形式要根据它所表示的时间来调整，这种虚拟条件句称之为错综复杂虚拟条件句。

往往是主句叙述与现在事实相反，谓语动词用would/should/might/could do,而从句叙述与过去事实相反，
谓语动词用had done.
* If I had studied hard, I would be sitting in the office comfortably now.
如果我早努力学习，我现在就会舒舒服服地坐在办公室里了。

（从句叙述与过去事实相反，谓语动词用had done,主句叙述与现在事实相反，谓语动词用would/should/could/might do）
（2）if引导虚拟条件句的省略。

If虚拟条件句中若含有were, should 或者助动词had，则可以把这三个词提前，省去if,出现省略倒装形式。

* If I were you, I would help him.
--Were I you, I would help him.
如果我是你，我会帮助他。

（if虚拟条件句中含有were，则可以省去if,把were提前）
* If he had known the result, he wouldn’t have shouted at mother.
--Had he known the result, he wouldn’t have shouted at his mother.
如果他早知道这个结果，他就不会朝他妈妈大声吼了。

（if虚拟条件句中含有助动词had,则可以省去if,把had提前）
* If an earthquake should happen, what would you do first? --Should an earthquake happen, what would you do first?
万一发生地震，你要先怎么做？（if虚拟条件句中含有should,则可
以省去if,把should提前）。