on the river?in the river?

on the river?in the river? 船是用in the river 还是on the river in the river与 on the river的区别 in the river和on the river有什么区别 on a river,on the river,in the river的区别 on the river in the river意思 是The ducks are swimming on the river 还是in the river?是There a the house in ( )front of the river is on fire 请名师指导：in the river 与on the river区别, 是there is a boat in the river还是there is a boat on the river [英语]在河上钓鱼的人是on the river还是in the river?