状语从句有哪几大类?怎么用?答:(一)时间状语从句 表示时间的状语从句可由when, as, while, whenever, after, before, till (until), since, once, as soon as (或the moment ), by the time, no sooner … than, hardly (scarcely) … when, every time等引导。e.g. When I came into the office, the teachers ...