一、定义
状语从句在复合句中由从句表示的状语称作状语从句，它可以用来修饰谓语(包括非谓语动词)、定语或状语，或是整个句子。
二、状语从句一般分为八大类
时间状语从句 地点状语从句
原因状语从句 目的状语从句
结果状语从句 条件状语从句
方式状语从句 让步状语从句
1. 时间状语从句
When ---当……时候, 通常指某一特定的时间点，主句与从句的动作同时发生。
When I opened the window, I saw him come up.
When --- 正在……的时候，突然…。通常主句是进行时或 be about to 时，在翻译的时候，when 可以译成没想到或突然。
I was walking along the street , when I met him.
When 当从句是进行时，主句是一般时，往往表示不满。
Someone knocked at the door when I was having breakfast.
When=after
When the children had gone to bed, she began to prepare her lessons.
While ---在……期间，往往指一段时间。
While we were inAmerica, we saw him twice.
While ---表示一种不满情绪，意思是这边在干某种重要的事，而另一边在享受等。
We are cleaning the classroom while they are playing the football.
As --- 一边……一边, 随着
She was doing her homework as she was listening to the music.
As --- 当……时，指一个动作紧接着一个动作发生，从句通常用进行时。
As I was going out, it began to rain.
The moment --- 一……就…… =as soon as , immediately,
---Did you remember to give Mary the money you owed her?
---Yes, I gave her the moment I saw her.
Not… until --- 直到……才
He didn’t leave the office until he finished the work.
Before --- 在……之前
The passengers should arrive at the airport an hour before the flight departs.
After --- 在…… 之后
The customer left the ticket counter after he had a quarrel with the ticket agent.
Since ---自从……, 通常主句用现在完成时
I have never been there again since I graduated from the university.
It is just a week since we arrived here.
As soon as --- 一……就……
Jack went to school as soon as he got well.
No sooner than --- 一……就……
no sooner… than… 用于句首要求倒装
Hardly …when…
Scarcely …when…
No sooner had he arrived than he went away again.
Once --- 一但……就……
Once you see him, you will never forget him.
Every time, each time 每次whenever 每当