The river, are covered with trees, is very long.
A. which banks
B. of which banks
C. whose the banks
D. the banks of which
网友回答
A. which banks
B. of which banks
C. whose the banks
D. the banks of which
解析：名词/代词+of+whom/which可引导非限制性定语从句,表示部分与整体的关系。C项应为whose banks。