状语成分的省略有什么规律答:常用于由when, while, before, after, whenever, till, until, since, once, as soon as等引导的时间状语从句。When (she was) very young, she began to learn to play the piano. 她很小时,就开始学习弹钢琴。When arriving, send me a telegram. (When you arrive, send me a telegram....