. 引导时间状语从句的五类引导词一引导时间状语从句的从属连词(以下称引导词)很多，为方便记忆，现作以下分类：1. 基本类包括before, after, when, while, as, since, till, until, once, as soon as 等。如：Did anyone call when I was out? 我不在家时谁来过电话吗?We have known each other since we were children. 我们从小认识。Youll feel better after you take the pills. 吃完药丸后你会感到好一些。Make sure that all the lights are off before you go to bed. 睡觉前一定要关灯。Dont promise him anything till weve had time to think about it. 在我们有时间考虑之前别答应他什么。2. 名词类即由名词词组充当引导词，包括the moment
