引導時間狀語從句：

　　1、表示“當……的時候”，相當于at the moment when。

　�。�1）When we got to the cinema,the film had been on for half an hour.當我們到電影院時，電影已經放映半小時了。

　　（2）She was writing a letter when I came in.當我進來時，她在寫信。

　　2、表示“一……就……”，相當于as soon as。

　�。�1）The students got up when the bell rang.鈴聲一響，學生們就起床了。

　�。�2）I’ll ring you up when I arrive in Beijing.我一到北京就給你打電話。

　　3、表示“就在這時；當時”，相當于just at the moment或just then。

　�。�1）We were about to start out when it began to rain heavily.我們正要啟程，就在這，天下起了大雨。

　�。�2）He had just returned from one business trip when he was asked to make another one.他剛剛出差回來，這時，又叫他再次出差。

　　4、表示“每當；每次”，相當于every time或whenever。

　　（1）She always turns to us for help when she is in trouble.每當她遇到困難，她總是向我們求助。

　�。�2）It is freezing cold here when it snows.每當這兒下雪，天氣就十分寒冷。

　　5、表示“當……之后”，相當于after the time that。

　�。�1）We went home when the film was over.電影結束以后，我們回家去了。

　�。�2）When she got home，she started to prepare supper.她回到家后，開始準備晚飯。