问题补充:
------Have you known each other for long?
------ Not very, we started to work in the ABC Motor Company.
A. before
B. since
C. when
D. after
答案:
A. before
(答案→)B. since
C. when
D. after
解析:考查介词,before 意思“在…之前”,since意思“自从”,when意思“当什么时候”,after意思“在…之后”,句子意思“自从我们开始在美国汽车公司”,所以选B