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.
While (I was) at college,I began to know him,a strange but able student.我在上大学时就开始认识他,一个奇怪但有能力的学生.
When arriving,send me a telegram.(When you arrive,send me a telegram.) 到达之后,来个电报.
Before leaving,turn off all the lights.(Before you leave,turn off all the lights.) 走之前,请关闭所有的灯.
Don’t come in until (you are) asked to.不叫你请你不要进来.
Whenever (it is )possible,you should come and help.不管什么时候只要有可能就来帮忙.
You should let us know the result as soon as(it is) possible.你应尽快让我们知道结果.
注：as在引导时间状语从句时,没有这种省略现象.我们不可说As walking,she found a nice shining thing on the ground.
