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。