赖世雄教你学英语语法
虚拟语气
3-1：基本句型结构
本虚拟语气中，if从句的动词要用过去完成时，主句则是助动词的过去时，再加have+过去分词。
句型如下：
if+主语+had+p.p主语+would/could/might/should/ought to+have+p.p
例：if i had arrived by three, i could have met him.
（要是我在三点前到，就能见到他了。）
if he had taken your advice, he might have been happier.
（要是他当时听了你的劝告，他可能会快乐些。）