18．The need to feed a growing population is putting much pressure on the world's supply of water．With 97% of the world's water too salty to be drunk or used in agriculture，the worldwide Supply of water needs careful management，especially in agriculture，Although the idea of a water shortage（短缺）seems strange to someone fortunate enough to live in a high rainfall country，many of the world's agricultural industries experience constant water shortages．
Although dams can be built to store water for agricultural use in dry areas and dry seasons，the costs of water redistribution（重新分配） are very high．Not only is there the co st of the engineering itself，but there is also an environmental cost to be considered．Where valleys（山谷） are flooded to create dams，houses are lost and wildlife homes destroyed．Besides，water may flow easily through pipes to fields，but it cannot be transported from one side of the world to the other．Each country must therefore rely on the management of its own water to supply its farming requirements．
This is particularly troubling for countries with agricultural industries in areas dependent on irrigation（灌溉）．In Texas，farmers'overuse of irrigation water has resulted in a 25% reduction of the water stores，In the Central Valley area of southwes tern USA，a huge water engineering project provided water for farming in dry valleys，but much of the water use has been poorly managed．
Saudi Arabia's attempts to grow wheat in desert areas have seen the pumping of huge quantities of irrigation（灌溉） water from underground reserves．Because there is no rainfall in these areas，such reserves can only decrease，and it is believed that fifty years of pumping will see them run dry．
72．From the first two paragraphs we learn thatC
A．much of the world's water is available for use
B．people in high rainfall countries feel lucky
C．the costs of water redistribution should be considered
D．water can be easily carried through pipes across th e world
73．Which of the follo wing is true？C
A．The water stores in Texas have been reduced by 75%．
B．Most industries in the world suffer from water shortages．
C．The underground water in Saudi Arabia might run out in 20 years．
D．Good management of water use resulted from the project in the Central Valley．
74．What is most likely to be discussed in the paragraph that follows？A
A．Steps to improving water use management．
B．Ways to reduce the costs of building dams．
C．Measures to deal with worldwide water shortages．
D．Approaches to handling the pressure on water supply．
75．The text is mainly aboutB
A．water supply and increasing population
B．water use management and agriculture
C．water redistribution and wildlife protection
D．water shortages and environmental protection．
分析 本文属于议论文阅读，作者主要向我们讲述了如今不断增长的人口对世界的水供应带来了压力，许多农业行业经常缺水，通过这篇文章作者向我们说明了如今水资源短缺的问题，呼吁我们要节约用水．
解答 72．C 细节理解题，根据第一段Although the idea of a water shortage（短缺）seems strange to someone fortunate enough to live in a high rainfall country，many of the world's agricultural industries experience constant water shortages．可知由于水资源短缺世界上许多农业行业经常缺水，由第二段the costs of water redistribution（重新分配） are very high．可知水再分配的成本是非常高的，因此我们应考虑水再分配的成本，故选C．
73．C 细节理解题，根据最后一段Because there is no rainfall in these areas，such reserves can only decrease，and it is believed that fifty years of pumping will see them run dry．可知沙特阿拉伯的水储备在减少，五十年内会干枯，可以推测在二十年内这的水可能被用完，因此C正确；误解分析：根据第三段In Texas，farmers'overuse of irrigation water has resulted in a 25% reduction of the water stores，可知减少了25%，因此A错；由第一段many of the world's agricultural industries experience constant water shortages．可知是很多农业缺水，因此B错；根据第三段but much of the water use has been poorly managed．可知是管理不善，因此D错；故选C．
74．A 推理判断题，根据第三段but much of the water use has been poorly managed．及第四段Because there is no rainfall in these areas，such reserves can only decrease，and it is believed that fifty years of pumping will see them run dry．可知如今的水资源管理不善，沙特阿拉伯的水在五十年内会干枯，因此下一段可能讲述如何完善水资源利用管理的措施，故选A．
75．B 主旨大意题，通读全文可知本文讲述了如今农业用水紧缺，而水资源也没有被很好的管理，因此本文讲述了水管理与农业，故选B．
点评 做阅读理解时要快速的浏览全文，把握文章主旨大意，带着问题回到原文，寻找细节或概括相应的答案，最后要理清作者写作思路．
