The river are covered with trees is polluted.
A. of which the banks
B. whose banks
C. the banks of which
D. A,B,C are right
网友回答
A. of which the banks
B. whose banks
C. the banks of which
(答案→)D. A,B,C are right
解析：考查定语从句关系代词的选择。关系代词代替的是先行词在定语从句中作定语。