重点语法

　　一、不同身份

　　1. 表示主从句的动作同时发生或几乎同时发生时，这类连词(组)有：when, while, as soon as。

　　例如：When I felt hungry, my friend gave me a hamburger. While I was working, my mother called me. Xiaoming let me know as soon as he bought the tickets.

　　2. 表示主从句的动作先后发生时，这类连词有：before, after。

　　例如：The thief had run away before the police arrived. After you finish the task, I will send you a present.

　　3. 表示主句动作为可持续性时，即主句谓语动词为持续性动词，这类连词有：until, since。

　　例如：I watched TV until my father came back. She has saved money since she got the job.

　　二、时态呼应

　　在时间状语从句中，主句和从句之间的时态呼应问题一般分下列三种情况：

　　1. 当从句表示“将来”的意义，用一般现在时，主句用一般将来时，即“主将从现”原则。例如：

　　She’ll be angry when she sees the broken window.

　　2. 主句是祈使句，时间状语从句用一般现在时。例如：

　　Turn off the tap when you brush your teeth.

　　3. 主句是一般过去时，时间状语从句也要用与过去相应的时态。例如：

　　He was fond of drawing when he was a child.