内容正文:
复合句的时态
复合句中,主句和从句的时态关系如下:
定语从句:定语从句的谓语和主句谓语之间没有必然关系;
宾语从句:宾语从句受主句影响,如果主句是现在时,从句可以用任何时态;如果主句是过去时,从句谓语一定要用过去的时态(一般过去时、过去进行时、过去将来时、过去完成时);如果从句是客观事实,从句谓语必须用现在时;
状语从句:主句和从句之间的时态一致问题一般分为下列几种情况:
1. 主情从现:主句中有情态动词时,从句用一般现在时表示将来。如:
①The traffic must stop when the lights turn red.
2. 主祈从现:主句是祈使句时,从句用一般现在时表示将来。如:
①Be careful when you cross the road.
3. 主将从现:主句用一般将来时,从句用一般现在时表示将来。如:
①I will visit my good friend when I have time.
②If she comes here tomorrow, I will go to the park with her.
3.Before: It will be + 时间段 + before + 一般现在时 ; it was + 时间段 + before + 一般过去时;Before引导的时间状语是过去时,主句可以用一般过去时或过去完成时
4. 宾语从句和状语从句同时出现。如:
①I don't know if he will come. If he comes, I will tell him about the accident.
②I don't know when he will come tomorrow. When he comes, I will tell him about the accident.
5. as when while 的区别和用法
1. 当从句中的谓语动词是持续性的动作,主句是短暂性动词可以用while, when或as。
eg:While / When / As I was walking down the street, I noticed a police car in front of the bank.
2. 当从句中的谓语