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．原因状语从句：
1. as引导的原因状语从句;
e.g. As he was too young, he couldn't join the army.
As I did not know how to get there, I had to ask the way.
2. because引导的原因状语从句；
e.g. Tom went to school late because he got up late.
Mary didn’t go to school because he was ill in hospital.
3. since和for引导的原因状语从句；
e.g. Don’t criticize him like that since he is only a child.
For my best friend will come to visit me, I must stay here.
三．结果状语从句：
1. so意为“因此”，引导结果状语从句；注意because不能与so连用；
e.g. Tom got a cold so he should go to see the doctor.
They study French at a young age, so they can speak it fluently now.
2.so …that或者such(…) that引导的结果状语从句，意为“以至于……；结果是……”;
(1) so +形容词/副词+that 从句;
(2)so+形容词+ a / an +单数名词+that 从句= such+ a / an + （形容词）+单数名词+that 从句;
(3)such + （形容词）+复数名词 / 不可数名词 + that从句
e.g. She is so lovely a girl that we love her very much.
She is such a lovely girl that we love her very much.
四．目的状语从句：so that，in order that等常用来引导目的状语从句，意为“为了，以便”。
e.g. Tom left home early so that he could catch the first bus.
We must try our best to study English in order that we can get better grades.
