—What do you think of teaching Bob?—I find it fun and challenging.It is a job you are doi

问题补充：

—What do you think of teaching，Bob?

—I find it fun and challenging.It is a job you are doing something serious but interesting.

A. where

B. which

C. when

D. that

答案：

A. where

B. which

C. when

D. that

解析：由于空格后面的分句不缺成分，且主句表语没有介词，不能作后一句的状语，而去掉“it is a job”后，这句意义还不完整，所以不会是强调句。排除D后，确认此句是定语从句。先行词是“a job”，带入定语从句中还原后有“you are doing something serious but interesting in the job”，所以关系词应为where，相当于“in which”。