问题补充:
We have heard of many cases some citizens ,especially some famous people, have suffered because personal information had been leaked.
A. why
B. which
C. as
D. where
答案:
A. why
B. which
C. as
(答案→)D. where
解析:定语从句的先行词cases在此意为“实例,情况”,根据从句的意思“在这些例子中(情境中)……”,先行词在从句中应该担当状语成分,表示in many cases,所以用where 来引导表示地点的定语从句。