A.When the ecological balance of the river is lost.B.When people consume more fish than they used to.C.When large numbers of algae, fish and birds are killed.D.When the production of marine petroleum is increased.
A.When the ecological balance of the river is lost.
B.When people consume more fish than they used to.
C.When large numbers of algae, fish and birds are killed.
D.When the production of marine petroleum is increased.