1、in the river，在河裡，是指在河水中，如魚、沉船等，尤其注意在河裡游泳也是用in the river。
2、on the river，在河上，是指在水面上，如船隻、水壩、漂浮物等。此外還可以指在河岸邊上，如村莊、市鎮等。
例句：On hot days we often bathe/go bathing in the river.天熱時我們常在河裡[去河裡]游泳。They were standing in the river spearing fish.他們站在河裡叉魚。Her sisters ducked her in the river.她的姐妹把她按到河裡。Her hat flew off and landed up in the river.她的帽子讓風颳跑落到河裡了。Some people just dump their rubbish in the river.有些人徑直往河裡倒垃圾。We heard wild duck quacking on the river.我們聽到野鴨子在河上呱呱叫。The river had been bridged with slabs of rock.用石板在河上架了橋。
兩個都正確要看用在哪裡方面。
1、in the river，在河裡，是指在河水中，如魚、沉船等，尤其注意在河裡游泳也是用in the river。
2、on the river，在河上，是指在水面上，如船隻、水壩、漂浮物等。此外還可以指在河岸邊上，如村莊、市鎮等。
例句：On hot days we often bathe/go bathing in the river.天熱時我們常在河裡[去河裡]游泳。They were standing in the river spearing fish.他們站在河裡叉魚。Her sisters ducked her in the river.她的姐妹把她按到河裡。Her hat flew off and landed up in the river.她的帽子讓風颳跑落到河裡了。Some people just dump their rubbish in the river.有些人徑直往河裡倒垃圾。We heard wild duck quacking on the river.我們聽到野鴨子在河上呱呱叫。The river had been bridged with slabs of rock.用石板在河上架了橋。