Pollution 1______ great harm to all the living things. The world we are living in is in 2______. Many years ago, there were 3______ sorts of trees and flowers, but now there are only 866. We are 4______ the earth, the air and the water and so on.
The things we should do
We should plant trees and flowers, save the water and animals and so on. We hope our world will be more and more 5______.