Question

By the time he was twelve, Edison ________ to make a living by himself .

A．would begin

B．has begun

C．had begun

D．was begun

Answer 1

C

时态题。By the time +过去时，主句谓语用过去完成时态 选C。 句意：到爱迪生十二岁时他已开始自己谋生了。