先看个例子：
This is the house (in) which we are living.
这里的in本来应该是在句子最后的，但定语从句里一般把介词提前。
你这句能把of放到后面吗？明显不可以啊！你不能把它理解成the river's的。
状语从句。。例如 stay at the place where you used to be.
D
The river's banks used to be covered with fruit trees.
The river is now seriously polluted.
c
是河的沿岸
