If虚拟条件从句的使用方法

1）if虚拟条件句：

例句：

如果你以前工作努力，你会升职的。

If you had worked hard,you would have been promoted.

if虚拟条件句的倒装：当省略if时，were、had、should可以放在句首进行倒装。

例如：

If you had worked hard before,you would have been promoted.

倒装句为：

Had you worked hard before,you would have been promoted.

2）If的错综时间虚拟：

当从句与主句的时间不一致时，主句和从句的动词形式要根据时间做出调整。

例如：

If you had studied hard before,you would be a college student now.

该局主句的now和从句的before都是明显的时间状语表示时间，从句是过去的虚拟于过去事实相反，因此用had done的形式，主句是对现在的虚拟因此用would do的形式。

3）可用其他语句代替If从句实现虚拟，常用的有but for、without、otherwise。

例如：

Without your help,we wouldn"t have finished the task.

等价于If you hadn"t helped us,we wouldn"t have finished the task。