A：What did you do last weekend?B：I worked at the university bookstore.A：I didn't know you had a job.B：Yeah,I‘m a cashier
问题描述：
A：What did you do last weekend?B：I worked at the university bookstore.A：I didn't know you had a job.B：Yeah,I‘m a cashier there.
为什么是you had a job ,那个工作B现在还在做呀。
答
I didn't know you had a job. B：Yeah,I‘m a cashier there.
解析：didn't 过去时,主句是过去时,从句也要用过去时.