单选题
As a result of pollution, Lake Erie, on the borders of the U. S. A. and Canada, now does not have many living things. Pollution in water is not simply a matter of "poisons" killing large numbers of fish overnight. Very often the effects of pollution are not noticed until many months or years later because the first organisms (生物) to be affected are either plants or planktons (浮游生物). These organisms are the food of fish, birds, and other creatures. When this food disappears, the fish and birds would die too. In this way a whole food chain can be wiped out, and it is not until dead fish and water birds are found at the river's edge or on the sea shore that people realize what is happening. Where do the substances that pollute the water come from? There are two main sources, sewage (生活污水) and industrial waste. As more detergent (洗涤剂) is used in the homes, more of it is finally put into our rivers, lakes and seas. Detergent harms water birds by breaking down the natural substances which keep their feathers waterproof. Sewage itself, if not properly treated, makes the water dirty and prevents all forms of life in rivers and the sea from receiving the oxygen they need. Industrial waste is even more harmful since there are more highly poisonous materials in it, such as copper and lead. So, if we want to stop this pollution, the answer is simple. Sewage and industrial waste must be made clean before flowing into rivers and seas. It may be already too late to save some rivers and lakes, but others can be saved if the correct action is taken at once.
单选题
Pollution in water is noticed ______. [A] when poisons are poured into water [B] when a great many fish and birds die [C] when the first organisms are affected [D] as soon as the balance of nature is destroyed
【正确答案】
B
【答案解析】[解析] 细节题。文章第二段提到“it is not until dead fish and water birds are found at the river's edge or on the sea shore that people realize what is happening”，意思是“人们只有在湖畔及海边发现死鱼、死鸟时，才意识到污染的存在”，所以答案是[B]。
单选题
The living things die because there is no ______ in the river or sea. [A] oxygen [B] poison [C] water [D] fish
【正确答案】
A
【答案解析】[解析] 细节题。根据第三段倒数第二句“Sewage itself, if not properly treated, makes the water dirty and prevents all forms of life in rivers and the sea from receiving the oxygen they need”(如果不对污水进行适当处理，就会污染水源，而且使水中的各种生物得不到它们所赖以生存的氧气)，可以判断生物死去是因为缺少氧气。此外，本题也可以运用常识作答。所以答案是[A]。
单选题
The way to stop water pollution is ______. [A] to put oxygen into the river [B] to realize the serious situation clearly [C] to make the waste materials harmless [D] to make special room in the sea for our waste
【正确答案】
C
【答案解析】[解析] 细节题。第四段提到阻止水污染的方法就是将生活污水及工业废水处理干净后再让其流入江河大海，即“So, if we want to stop this pollution, the answer is simple. Sewage and industrial waste must be made clean before flowing into rivers and seas”。而且对比四个选项，[A]、[B]、[D]都没有在文中提到，只有[C]项的意思与其相符。
单选题
What is the meaning of the word "waterproof" in the fourth paragraph? [A] Covered with water. [B] Full of water. [C] Cleaned by water. [D] Not allowing water to go through.