问题补充:
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
答案:
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。