A．A fish may die because rivers may contain industrial wastes
B．B it may be dangerous to swim in a river because the water may contain pesticides
C．C EPA is responsible for causing serious water pollution in America
D．D water pollution is rather serious in America
A．A they are rushed into agricultural fields and yards
B．B they are choked by the water body
C．C the poisonous algae have killed them
D．D the fast-growing algae have used up the oxygen in the water where they live
A．A cutting down too many trees may also cause water pollution
B．B erosion is caused by wind and rain alone
C．C there are no longer desirable fish in the world
D．D trout and salmon usually spawn in silt
A．A Fish as a Source of Protein
B．B The Increasing World Oil Production
C．C Oil Spills and Pollution of the Sea
D．D A World-famous Oil Tanker