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

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：

(答案→)A. where

B. Which

C. When

D. that

解析：考查定语从句的用法。定语从句主谓宾完整，说明应该填关系副词，先行词为a job，定语从句的意思是在这个工作中……，所以答案用where引导的定语从句。