状语从句是指被用来修饰主句中谓语动词的从句，一般用来表示时间、原因、条件、目的、结果等等，可以用不同的连词引导，如when，if，because，although，so that等等。
英语状语从句可分为以下几种种类：
- 时间状语从句：表示时间关系，常用连接词有when, while, before, after, as soon as, until, since等。例如：“When I arrived at the station, the train had already left.”
- 原因状语从句：表示原因或理由，常用连接词有because, for, as, since, now that等。例如：“Since it is raining, I will stay indoors.”
- 条件状语从句：表示条件或假设，常用连接词有if, unless, provided that, in case等。例如：“If you come with me, I will show you around the city.”
- 结果状语从句：表示结果或后果，常用连接词有so that, such that, that等。例如：“She studied hard so that she could pass her exams.”
- 目的状语从句：表示目的或意图，常用连接词有so that, in order that等。例如：“He worked overtime so that he could finish the project on time.”
- 让步状语从句：表示让步或转折，常用连接词有although, even though, though, even if等。例如：“Although it was raining heavily, they still went out for a walk.”
- 比较状语从句：表示比较，常用连接词有as, than等。例如：“She is as tall as her sister.”和“She speaks English better than I do.”
- 方式状语从句：表示方式或方法，常用连接词有as, as if, as though等。例如：“She danced as if nobody was watching.”
- 地点状语从句：表示地点，常用的连词有where, wherever等。例如：“I’ll meet you where we first met.”