it wasn't long ()he joined the job.A that B before C until D and

问题描述:

it wasn't long ()he joined the job.A that B before C until D and
为什么选B

not long before 是个词组吧,固定搭配
在他参加这个工作之前时间不是很长,也就是:没过多久他就参加这个工作了