缺词填空The ABC Island to be the home of many wild animals.It was very quiet and people
could only go there by s＿.But now there are more roads,buildings and people.A new fectory was built near it.The factory dumped its waste into the river.The poison in the waste killed fidh and plants and polluted the river.The government realized it and did something to stop it.Now the river is b＿ clean again.