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：
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什么时候做
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什么地点做
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在什么条件下做
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为了什么目的做
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用什么方式做
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和谁对比着做
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即使发了什么也得做
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做了有什么结果
等等等
状语从句类型
常用的引导词
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。
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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。
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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。
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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。
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We will finish the project before winter comes. 我们将在冬天来临之前完成这项工程。
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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。
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I will visit you after this semester finishes. 这个学期结束后，我将去访问你。
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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
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I was cooking, while he was playing video games. 在我做饭时，他在打游戏。
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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
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The thief had run away by the time the police arrived. 警察来的时候，小偷已经跑了。
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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
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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
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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。
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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
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I will pay you as soon as you deliver the goods. 你发货后，我马上付钱。
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Please call me as soon as you arrive. 在你到达后，请马上给我电话。
Whenever, every time
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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。
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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
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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。
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The second time I met her, I fell in love with her. 第二次和她见面，我爱上她。
