You count such a watch by the time he starts his class.

　　你總是掐著他開(kāi)始上課的時(shí)間。

　　Most of the workers had already rung in by the time I arrived.

　　我到的時(shí)候，大多數(shù)工人都已簽到了。

　　By the time she left college, she had been an excellent student.

　　到她大學(xué)畢業(yè)的時(shí)候，她已經(jīng)是一個(gè)優(yōu)秀的學(xué)生了。