A housing bubble is an economic situation occurs when house prices rise much too fast.
A. which
B. where
C. what
D. why
网友回答
(答案→)A. which
B. where
C. what
D. why
解析：
试题分析:考查定语从句。从结构判断situation为先行词，后面跟定语从句，从句中缺少主语，所以用关系代词which。B，D选项是关系副词，在从句中不做主语，C选项what不引导定语从句。句意：房地产泡沫是一种经济形势，这种经济形势只有当房价上升太快的时候才会发生。所以A选项正确。