语法在任何一门语言中都是很难学的，英语也不例外，过去时、现在时、将来时、完成式、被动式、条件句等等，就像雷区一样。更糟糕的是，我们在每一个阶段都学语法规则，最后发现学到中高级、高级阶段，你有时要做些变通甚至可以打破语法规则。
条件句的结构
条件句通常使用if，包含2个分句，主句是will 或would 加动词，从句是用If引导。
I’ll drive tonight(main clause)if your car is broken (subordinate clause).
条件句的分句的顺序是可以改变的。如果我们以if从句开头，要用逗号把2个句子分开.
If your car is broken(subordinate clause)I’ll drive tonight(main clause).
条件句的不同形式
零条件句Zero Conditional,用于陈述普遍真理
If you heat iceit melts.
or
Ice meltsif you heat it.
第一条件句1stConditional,用来陈述将来
If it rains tonight,I will get wet.
or
I will get wetif it rains tonight.
·第二条件句2ndConditional,用来陈述不可能发生的事情
If I had a million dollars I would buy lots of cars!
or
I would buy lots of carsif I had a million dollars!
·第三条件句3rdConditional,用来推测过去，表达一种遗憾。
If I had studied English more at school, I would have passed the BEC higher!
or
I would have passed BEC higherif I had studied English more at school!
你的英语越熟练，问题可能越会随之而来。你会发现英美人通常会混和使用条件句的结构，这时你不得不做些变通。不过混合条件句就完全是另外的内容了。
先练习以上这几种条件句，混合条件句下次我们再探讨。
