Jack’s sister has been a tour guide two years ago.A. forB. sinceC. aboutD. in

问题补充：

Jack’s sister has been a tour guide two years ago.

A. for

B. since

C. about

D. in

答案：

A. for

(答案→)B. since

C. about

D. in

解析：考查介词。句意：自两年前以来，jack的妹妹就一直是导游，故选B。