专题十二 状语从句 状语从句在句中相当于副词作状语 , 又叫副词性从句。在句子中可修饰谓语（或其他动词）、形容词、副词或是整个句子，它可以用来表示时间、地点、原因、目的、结果、条件、方式、比较、让步等。状语从句通常由一个连词引导，也可以由一个起连词作用的词组引导。状语从句是近几年高考试题中常见的一个重要考点。 状语从句的分类及常用连接词种类从属连词例句说明时间状语从句 whenwhenever When I came into the room, he was writing a letter.You can eat food free in my restaurant whenever you like. when 指“某一具体的时间”；whenever 指“在任何一个不具体的时间”。 whileWhile John was reading, I was watching TV. I stayed while he was away. while 指“在……期间”，引导的动作必须是持续性的。 asThey talked as they walked along the river.As time goes by, I like China better. as （一边……一边）表示持续性动作，强调主句和从句动作同时发生；随着。 bef-oreBefore I could get in a word, the tailor had measured me. ( 还没来得及就…… ) We hadn‘t run a mile before he felt tired.( 还没……就…… )We had sailed 4 days before we saw land.( …… 才…… )Please write it down before you forget it. ( 趁还没……就…… ) before 引导从句时，词义非常灵活。 Afte-rHe arrived after the game started. tillunti-lHe remained there till/until she arrived.She won’t go to bed till/until he returns home.It is not until he returns home that she will go to bed.Not until he returns home will she go to bed. 若主句动作是持续性动作，常用肯定式，表示“直到……为止”；若主句动作是瞬间动词，要用否定式，表“直……才”，“在……以前不”；从句放在句首时表示强调，一般用 until 并引起部分倒装。 时间状语从句 sinceGreat changes have taken place in China since 1978. since 在时间状语从句中，不论用短暂动词、延续动词还是状态动词的一般过去时，通常都表示从动作或状态的完成或结束时算起，主句时态多用现在完成时。 as soon as hardly...when no sooner...thanthe momentthe...
