By the time he was 15,the boy___to make a living by himself

问题描述:

By the time he was 15,the boy___to make a living by himself
A.would begin B.has begun C.had begun D.began

选 C
by the time he was 15 ,意思是:到他15岁为止
这种时间状语用于过去完成时.
意思是:到他15岁为止,这个男孩已经开始独自谋生了.