定义及分类：在句中作状语的从句叫状语从句，也叫副词性从句。状语从句由从属连词引导，可表示时间、地点、条件、原因、结果、目的、让步、比较、方式等。状语从句连词一览表：状语从句名称连词时间状语从句when，as，while，since，before，after，till，until ,once，scarcely...when，hardly...when，no sooner...than,as soon as = the moment = the minute = the second = the instant =immediately = directly = instantly，by the time，every time，each time，地点状语从句where，条件状语从句if，unless，only if，providing=providedthat，in casethat，so long as=as long as，on condition that, once，supposing...原因状语从句because，since，now that，as，seeing that，considering that结果状语从句sucha，an...that，so...that，so that，
