状语是主要是修饰谓语的，状语从句也不例外。
状语作为副词还可以修饰别的成分，如定语、状语、非谓语动词和整个句子。
状语从句主要有以下九种，也就是表示谓语动词可以被从九个不同的方面被修饰：
什么时候做
什么地点做
在什么条件下做
为了什么目的做
用什么方式做
和谁对比着做
即使发了什么也得做
做了有什么结果
等等等
状语从句类型
常用的引导词
常用的时间状语引导词及释义
详解
when
在我小时候，我喜欢听收音机
when表示at that moment，when引导的从句用一般现在时表将来。
I will tell you when you finish your work. 当你把工作完成后，我将会告诉你。主将从现。
I was talking with my mother when the rain arrived. 大雨来临时，我正在和妈妈说话。主过从过。
You can call me your friend when you behave like a friend. 当你做的像个朋友时，你再把我称为你的朋友吧。主现从现
我觉得复合句的“主句一般现在时，从句时态不限”的规律不能应用在when引导的从句里。
I tell you I had been married. 我告诉你，我早已结婚了。主句一般现在时，从句过去完成时作为宾语从句有意义。但在状语从句里，没意义。我觉得该主现从现。
before
before 引导的从句用一般现在时表将来。
We will finish the project before winter comes. 我们将在冬天来临之前完成这项工程。
The train had left before they arrived the station. 在他们赶到火车站之前，火车已经开走了。
after
用一般现在时表将来。
I will visit you after this semester finishes. 这个学期结束后，我将去访问你。
You can have your lunch after I leave。我走后你才可以吃饭。
while, as
持续性动作用这两个
I was cooking, while he was playing video games. 在我做饭时，他在打游戏。
As we were saying goodbye to him, we began to shed tears. 当我们和他说再见时，我们开始流泪。
by the time
主句用完成时
The thief had run away by the time the police arrived. 警察来的时候，小偷已经跑了。
I will have been starved by the time you arrive. 等着你来，我早被饿死了。
till until
只跟一般现在时和一般过去式，用一般现在时表将来。 till一般只用于口语
I will wait for you till you change your mind. 我会一直等你，直到你改变主意。
since
自从
He has been drunk 7 days a week since his girl friend left him. 自从女友离开后，他就成了个一周醉七天的醉鬼。
My family have lived in the city since the 1990s. 从上世纪90年代开始，我家就在城市里居住了。
as soon as
在某事发生后立即发生，主将从现
I will pay you as soon as you deliver the goods. 你发货后，我马上付钱。
Please call me as soon as you arrive. 在你到达后，请马上给我电话。
Whenever, every time
Whenever you appear in front of me, I feel disgusted. 每当你出现在我面前，我就觉得恶心。
Every time you go away, you take a piece of me with you. 每次你离开，都让我的心残缺不全。
The +序数词+time
The first time I saw the Yangtze River, I was intimidated by its grandness. 第一次见长江，我就被它的雄伟镇住了。
The second time I met her, I fell in love with her. 第二次和她见面，我爱上她。