— 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

规划阶段对规划河流或河段内的区域构造应了解主要构造单元、褶皱和断裂的类型、产状、规模和（），历史地震情况和地震烈度等。

A.地震活动史

B.构造活动史

C.地震记录

D.构造运动