57--61 DDCAD

　　57.主旨题。第一段后半部分引出主旨“They have trouble getting enough clean water for their basic needs.This situation may soon become common all around the world，...lack of clean water may be one of the biggest issues in the twenty-first century.”。第二段谈及clean water变少的两个主要原因，第三段告诉读者既然可饮用水减少，人们就拼命掘井。然而井水也被污染。第四段说一旦地下水被污染，就不是短时间内可以恢复的。第五段阐述地下水污染的三个主要原因(化学物质、农业和废物)。最后一段再次重申地下水问题的重要性并呼吁全球政府采取措施。因此，正确答案为D项。

　　58.细节推断题。请看上下文“They have trouble getting enough clean water for their basic needs.This situation may soon become common all around the world，...lack of clean water may be one of the biggest issues in the twenty-first century”，由此可推断将有越来越多的人喝不上、用不上干净的水，故正确答案D项。

　　59.细节选择题。第二段讲干净的水减少的原因“On the one hand，people are using more water than ever before...population of the world has more than doubled...On the other hand，many sources of surface water...--are too polluted and unhealthy for use as drinking water.”，即一方面人均用水量比以前增加，人口翻番;另一方面地表水污染严重，不适合饮用。因此正确答案为C项。

　　60.细节题。第三段中的“people in the United States began to find chemicals in their well water，...Weldon Spring，...，for example，..”说明美国科学家发现Weldon Spring这些地方的井水里有化学物质。因此正确答案为A项。

　　61.推断题。倒数第二段“Industrial sites...are one cause of underground water pollution... Underground water pollution is also caused by modern farming methods，which require the use of large amounts of chemicals in the fields.And finally，yet another important cause of underground water pollution is waste”中清楚地说明了地下水污染的三大原因，即化学物质、农业化肥和废弃物。因此正确答案为D项。