短文改错

　　Our school lies on the foot of a mountain with a small river passes by in front. It used to look like a beautiful garden. In the garden there are ever-green trees and all kinds of flowers in the school yard all years round.

　　But great changes have been taken place after a chemical factory was built near our school a year ago. It produces various poisonous gases and pours a lot of waste water into a river. This has terrible polluted the surroundings of our school.

　　I think that the local government must takes steps to protect our surroundings and prevent from being polluted.