状语从句的讲解和练习 在复合句中修饰主句中的动词、形容词或副词等的句子叫状语从句。状语从句根据它表达的意义的不同可分为：时间状语从句、原因状语从句、条件状语从句、比较方式状语从句、目的状语从句、结果状语从句和让步状语从句。如果状语从句放在主句前，通常在从句后用逗号隔开。 （一）时间状语从句 其连接词有：when，while，before，after，since，till（until），as soon as 等。由这些连词引导的主从复合句中的主句和从句谓语动词发生的时间有三种情况，即同时发生和先后发生。因此在运用时间状语从句时，特别要注意主句和从句之间的时态呼应。 1. when 引导的从句 有时主句的动作和从句的动作同时发生，有时主句的动作在前，从句的动作在后。如果主句用一般将来时，则从句就要用一般现在时。 Tom will go to see her when he has time. It was raining when I left the hospital. The film had already began when I got to the cinema. 2. 由 while 引导的从句 表示正在进行某一动作时另一动作发生了；还可以表示某个动作还在进行的同时，另一个动作也在进行之中。例如： While he was reading, the telephone rang. While we were boating on the lake, we saw a fish jump out of the water. While my sister was watching TV, I was writing. While Dad was washing his car, Mum was cooking. 3. 由 before 引导的从句 在由 before 引导的从句中，一般来说主句的动作发生在从句的动作之前，主从句的动词都用过去时。例如： Wei Fang had cut the meat into pieces before her mother started cooking. He didn't know little Chinese before he came to China. My brother studied in No.1 Middle School before he joined the army. 4. 由after 引导的从句 由after 引导的从句表示主句的动作发生在从句之后，为了表明动作的先后顺序，这是主句的动作用一般过去时，而从句的动作用过去完成时。有时主从句的动词都用过去时。例如： After he had finished his homework, he went home. After the bell rang, all the students rushed out of the classroom. 5. 由since 引导的从句 在由since 引导的复合句中，从句动词用一般过去时，主句动词用现在完成时。...
