问题补充：
Can you think of some cases drivers obviously knew the traffic rules but did not obey them.
A. which
B. as
C. where
D. that
答案：
A. which
B. as
(答案→)C. where
D. that
解析： 考查定语从句的关系词。先行词是some cases，后面从句drivers obviously knew the traffic rules but did not obey them缺少状语，当case，situation,position,condition等这类抽象名词作先行词，且后面定从缺少状语时，定从通常用where引导。所以选C。
