问你们一道初三英语题

这话有问题，可能漏打了，可参考二楼意见
the river是先行词，从句是in which I can swim ，关系代词是which，in是介词，可以放在关系代词之前，也可以放在swim之后，即which I can swim in也可以

从句 in which i can swim
先行词 in which

in which i can swim是从句，先行词是in which,a piece of cake

这是个定语从句，从句是i can swim in ， 先行词是river， 关系代词是which

从句是in which I can swim.
先行词是river
整句相当与can I swim in the river?
或变形为Is the river which I can swim in?

从句是I can swim(修饰the river)先行词是which