when引导的时间状语从句是怎样的？举例
时间状语从句:
连接时间状语从句的连接词有:
(1) 连词：when, while, as。 它们都表示当…时候的意思。如果主句和从句的动作同时发生且都是进行时
态，只用while, as。 其他情况下when, while, as通用。
1 When he came in, I was listening to the radio．
2 As I was wandering in the street, I met her。
3 While (as) I was watching TV, my mum was cooking in the kitchen。
(2) 连词befor...全部
时间状语从句:
连接时间状语从句的连接词有:
(1) 连词：when, while, as。 它们都表示当…时候的意思。如果主句和从句的动作同时发生且都是进行时
态，只用while, as。
其他情况下when, while, as通用。
1 When he came in, I was listening to the radio．
2 As I was wandering in the street, I met her。
3 While (as) I was watching TV, my mum was cooking in the kitchen。
(2) 连词before, after, since, until(till)。
当他们表示时间时，他们既是介词又是连词。
{ He usually drinks a cup of tea before he goes to school。
连词
He usually drinks a cup of tea before going to school。
介词
{
He usually drinks a cup of coffee after he comes back from school。
连词
He usually drinks a cup of coffee after coming back from school。
介词
{
I have lived in Dalian since my son was born in 1999。
连词
通常情况下，主句用现在完成时，从句用一般过去时。
I have lived in Dalian since 1999。
介词
{
I will wait here until(till) you finish your job。
连词
I will wait here until(till) 8pm。
介词
(3) 词组：as soon as
{ I will tell him as soon as he comes back。
As soon as she finishes her homework, she will play tennis。
通常情况下，主句用一般将来时，as soon as 引导的从句用一般现在时。收起
