省略If的虚拟条件句的具体用法是怎样的？

在条件句中可省略if，把were, 助动词had, should提到句首，变为倒装句式。如：

If I were at school again, I would study harder．

→Were I at school again, I would study harder．

如果我还有上学的机会，我会更加努力地学习。

If you had come earlier，you would catch the bus．

→Had you come earlier, you would catch the bus．

如果你来得早些，你就能赶上公共汽车。

If I had enough money, I would help her.

→Had I enough money, I would help her. （x）

If it should rain tomorrow, we would not go climbing．

→Should it rain tomorrow, we would not go climbing．

如果明天下雨的话。我们就不去登山了。

If they were here, they should agree with me.

→Were they here, they should agree with me.

如果他们在这儿的话，他们会和我一个立场。

If he had learnt about driving, he should have had a car.→

Had he learnt about driving, he should have had a car.

如果他学了开车的话，他就有一辆自己的车了。

If they were here now, they could help us.→

Were they here now, they could help us.

他们现在在的话，就会帮助我们了。