注: 例:1)He often got up at six in the morning last year. 2) Mike was a middle school student in 1990. 例 1) He said he would go to Bei jing the next day. 2) He asked who was going there.
例 1) At that time he was watching TV. 2 ) When he came in, I was reading a newspaper. 例 1) As soon as we got to the railwaystation, the train had left. 2) By the end of last term we had received four books.