[单项选择]

Water Pollution

The demand for freshwater rises continuously as the world’s population grows. From 1940 to 1990, withdrawal of fresh water from rivers, lakes, reservoirs, and other sources has increased fourfold. Of the water consumed each year, 69 percent is used for agriculture, 23 percent for industry, and 8 percent for domestic uses.
Sewage, industrial wastes, and agricultural chemicals such as fertilizers and pesticides are the main causes of water pollution. In 1995, the US Environmental Protection Agency (EPA) reported that about 37 percent of the country’s lakes and estuaries, and 36 percent of its rivers. are too polluted for basic uses such as fishing or swimming, during all or part of the year. In developing nations, over 95 percent of urban sewage is discharged untreated into rivers and bays, creating a major human health hazard.
Water runoff carries fertilizing chemicals such as phosphates and nitrates from agricult
A. they are rushed into agricultural fields and yards
B. they are choked by the water body
C. the poisonous algae have killed them
D. the fast-growing algae have used up the oxygen in the water where they live

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