单选题 The river, ______ the bank are covered with trees, is very long.
【正确答案】 C
【答案解析】[解析] 名词或代词+关系代词whom/which可以引导非限定性定语从句,表示部分与整体的关系,作用相当于whose+名词,of which the bank=the bank of which=whose bank,因此答案为C。