1. 主要子句述语动词为简单现在式、现在完成式或简单未来式时,子句的述语动词可根据意义,用所需的任何时态。
I don't know why John didn't come for the dinner.
我不知道约翰为什么今天没有来赴宴。
I know why he didn't come to the meeting.
我知道他为什么没有参加会议。
2. 主要子句的述语动词是过去时态,子句的述语动词一般也要用过去时态的某种形式。
He said he was in the hospital.
他说他在医院呢。
He told me he was holding a wire pole.
他告诉我正抓着一根电线杆。
He said he was going to take little pebbles out from his shoes.
他说他要把鞋里的小石子弄出来。
The passerby thought he had got an electric shock.
那个过路人以为他触电了呢。
I didn't know you were also here.
我(刚才)不知道你也在这里。
子句与主要子句的动作同时发生,子句用简单过去式或过去进行式。
They said they were having an important meeting.
他们说他们正在开一个重要的会议。
主要子句的动作发生时,子句的动作正在进行,子句用过去进行式。
I heard that he had been writing novels.
我听说他一直在写小说。
子句动作在主要子句动作之前,并强调一直再进行,子句用过去完成进行式。
I was afraid that I should lose my way in the dark.
我怕天黑我会迷路。
子句动作在主要子句动作之后,子句用简单过去未来式。
3. 子句如有绝对的时间副词或片语,其述语动词一般用简单过去式代替过去完成式。
He said he was beaten by someone this morning.
他说今天早上他被人打了。
He told me he was born in 1928.
他告诉我他生于1928年。
4. 子句表示普遍真理、客观规律或现在的习惯时,其述语动词用现在时态。
The teacher told the pupils that the earth is round.
老师告诉学生们地球是圆的。
5. 形容词子句和表示原因,比较等的副词子句的述语动词,一般不受时态一致的一般规则的制约,可用符合文意的任何时态。
He spoke English better than you speak it now.
他过去英语讲的比你现在讲的好。
6. 主要子句是未来式,表示时间或条件的副词子句要用简单现在式代替无意志的未来式。
He will pay for the dinner if he is here.
如果他来这里，他就会付饭费。
If it rains, I shall not go.
如果下雨,我就不去了。
7. 主要子句是未来式,副词子句如表示意志未来,仍须用带will的未来式。
If she will come, we shall be very happy.
如果她愿意来,我们将非常高兴。