一． 状语从句：
1.定义：用作状语的句子，相当于副词的用法；
2.分类：时间状语从句；原因状语从句；条件状语从家；结果状语从句；让步状语从句等。
二．让步状语从句：
1. though, although, even if, even though意为“虽然”，不与but连用，但可以与yet(但是)连用，引导的让步状语从句；
e.g. Though Tom studies English only a few years, he can speak it very well.
Though they had been warned of the storm, the farmers were still working in the fields.
Even if I am invited, I won’t go.
注意：as if, as though等引导的方式状语从句，意为“好像，似乎”；
e.g. She talks about Rome as though she had been there herself.
He treats me as if I were a stranger.
2. no matter+特殊疑问词=特殊疑问词+ever 引导的让步状语从句;
e.g. Wherever you go, I will go with you.
= No matter where you go, I will go with you.
No matter what I did, my parents will support me.
3. while引导让步状语从句时，相当于although，但只能防御句首。
e.g. While I understand your idea, I don’t agree with you.
Although/While he has many shortcomings, he has a lot of advantages.
三．条件状语从句：
1. if引导的条件状语从句；
e.g. If you work hard, you'll make great progress.
If we were given more time, we could do it much better.
2. unless“除非”，相当于if not，引导条件状语从句；遵循“主将从现”的原则；
e.g. Everything will get worse unless we take action at once.
You will get worse grades unless you study hard.
3. as long as或者so long as 引导的条件状语从句；意为”只要”；
e.g. As long as you stay here, you will know the thing.
So long as you keep reading, you will have a better understanding.
4. supposing/suppose(假如)；provided/providing(假如)；given(假设)等引导的条件状语从句；
e.g. Supposing (that) this is not the right way to the bank, what shall we do?
Provided (that) they get happiness from playing computer games, they will continue to play them.
Given (that) Tom doesn’t go with me, what shall I do?
5. 在条件状语从句中，如果主句为一般将来时，那么从句需用一般现在时。
e.g. If you are interested in this book, I will buy it for you.
If you can help Tom, he will be happy.
