问题补充：
In front of our house we used to swim.
A. a river lies that
B. does a river lie where
C. lies a river which
D. lies a river where
答案：
A. a river lies that
B. does a river lie where
C. lies a river which
(答案→)D. lies a river where
解析：考查 倒装和定语从句的关系词。In front of our house是介词短语，介词短语放在句首时，句子要完全倒装，排除A,B；a river是先行词，定语从句 we used to swim中缺少地点状语，要用where引导。所以选D。
