in the river comes a boat,making pollution,with some people

There is a boat in the river Some boat's a----- in the river.请问A和后面什么单词 Some people （）swimming in the river now.A.is 是there is a boat in the river还是there is a boat on the river Look!Some chilren are sitting a boat the river There's a boat in the m___ of the river. People are worrying___the pollution of the air. A.in B.with some people _________________（boat）in the lake People can travel in the river by ( )( )( )on the boat.人们可以乘 There was a boat on the river with a woman on it怎么翻译 a boat( )the river填介词 we can see a boat the river