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。