Rivers in the poorest developing countries have shown marked falls in levels of dissolved oxygen---a key indicator of increased pollution by sewage. An estimated 90% of sewage in developing countries is discharged into rivers, lakes and seas without any treatment. To make things worse, supplies of fresh water that might dilute the sewage are dwindling in many areas.

Asia's rivers, which are among the most polluted in the world, contain ten times as many bacteria from human waste as waterways in rich countries. They contain far more lead too, much of it from industrial effluents . The biggest cause of water pollution in developing countries is sewage, and its most important effect is on human health.

Each year, according to the World Health Organization, 900m people suffer from diarrhea or diseases spread by contaminated water such as typhoid and cholera , and at least as many from diseases caused by intestinal worms . Better water supplies and sanitation would cut the incidence of such diseases dramatically. In terms of the number of people it kills, dirty water is probably the world's most serious pollution problem.



Questions:

1. The decrease of dissolved oxygen indicates

A. the fall of the poorest developing countries

B. the increase of pollution by sewage

C. the fall of fresh water supplies

D. the worse things

2. Contaminated water can cause such diseases as

A. typhoid

B. cholera

C. diarrhea

D. all of the above

3. The author thinks that

A. Asia's polluted rivers contain a few bacteria

B. Better sanitation can solve some pollution problem

C. One can find no lead in the Asia's polluted rivers

D. Better water supplies would dilute the sewage













Answers:BDC

阅读时间：

正确率：





Words:

cholera 霍乱

diarrhea 腹泻

dilute 稀释

dissolve 分解，溶解

dwindle 缩小

effluent 流出物，废水，废物

incidence 发生率，发生程度

intestinal 肠的

sanitation 卫生，卫生设备

sewage 污水，污物

typhoid 伤寒
关键字:英语阅读
生词表: