by the time our teacher came in ,we had started speaking English.
在老师进来前,我们都已经开始讲英语了.
by the time when got to the bus station,the bus had left.
在我们到达车站时,汽车早就开走了.
By the end of last year,another new gymnasium had been completed.(2003上海·春）到去年年底,又有一座新体育馆峻工了.