1.The disposal of _______ sewage in rivers and oceans leads to water pollution (treat)

2.Water pollution can be caused by _______ subtances from factories. (poison)

3. Cutting down trees causes a lot of ______ damage. (environment)

4.Sewage from the market may make water in rivers and lakes ______. (Contaminate)

5.There is a link between exposure to ______ and cancer. (radiate)