高中英语语法复习专题 状语从句
一、考点聚焦
1、时间状语从句
（1）as、when、while用法一览表。
类别 作 用 例 句
as as表示“当……的时候”，往往和when/ while通用，但它着重强调主句与从句的动作或事情同时或几乎同时发生。 She came up as I was cooking.(同时)
The runners started as the gun went off.(几乎同时)
when (at or during the time that )既可以表示在某一点的时候，又可表示在某一段时间内，主句与从句的动作或事情可以同时发生也可以先后发生。 It was raining when we arrived.(指时间点)
When we were at school, we went to the library every day.(在一段时间内)
while while意思是“当……的时候”或“在某一段时间里”。主句中的动作或事情在从句中的动作或事情的进展过程中发生，从句中的动词一般要用延续性动词。在when表示a period of time时，两者可以互换。 Please don’t talk so loud while others are working.
He fell asleep while/when reading. Strike while the iron is hot.(用as或when不可，这里的while意思是“趁……”)
（2）引导时间状语从句的连接词除上述外还有：
①till, not … until …, until, before, since
Don’t get off the bus until it has stopped.
He waited for his father until(till)it was twelve o’clock.
It will be five years before he returns from England.
②hardly / scarcely … when, no sooner … than, as soon as once
表示“一……就”