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  3. Desertification (沙漠化) in the dry United States is very serious. Groundwater supplies beneath vast stretches of land are dropping

Desertification (沙漠化) in the dry United States is very serious. Groundwater supplies beneath vast stretches of land are dropping

admin2009-09-12  61
问题 Desertification (沙漠化) in the dry United States is very serious. Groundwater supplies beneath vast stretches of land are dropping rapidly. Many river systems have dried up. Hundreds of thousands of acres of previously irrigated cropland have been abandoned to wind or weeds. Several million acres of natural grassland are eroded at unnaturally high rates as a result of cultivation or overgrazing (过度放牧). All told, about 225 million acres of land are under severe desertification.
Federal subsidies (补贴) encourage the exploitation of dry land resources. Low-interest loans for irrigation and other water delivery systems encourage farmers and industry to mine groundwater. Federal disaster relief and commodity program encourage dry-land farmers to plow up natural grassland to plant crops such as wheat, especially, cotton. Federal grazing fees that are well below the free market price encourage over-grazing of the commons. The market, too, provides powerful incentives (激励) to exploit dry land resources beyond their carrying capacity.
The incentives to exploit dry land resources are greater than ever. The government is now offering huge new subsidies to produce synthetic fuel from coal oil as well as alcohol fuel from crops. Moreover, commodity prices are on the rise; and they will provide farmers and agricultural businesses with powerful incentives to overexploit arid land resources. The existing federal government cost-share programs designed to help finance the conservation as soil, water, and vegetation are pale in comparison to such incentives.
In the final analysis, when viewed in the national perspective, the effects on agriculture are the most troublesome aspect of desertification in the US. For it comes at a time when we are losing over a million acres of rain-watered crop and grass land per year to higher uses—shopping centers, industrial parks, housing development, and waste dump—regardless of the economic need of the US to export agricultural products or of the world’s need US food and fiber. Today the dry West accounts for 20 percent of the nation’s total agricultural output. If the US is, as it appears, well in its way toward overdrawing the dry land resources, then the policy choice is simply to pay now for the appropriate remedies or pay for later when productive benefits from arid land resources have been both realized and largely terminated.
选项 A、The shrinking of forest coverage.
B、The lack of water supplies.
C、A quickly decreasing production of crops.
D、A large area of cropland changed into grassland.
答案B
解析 由题干中的severe desertification定位到原文首段前三句Desertification in the dry United States is very serious. Groundwater supplies beneath vast stretches of land are dropping rapidly．Many river systems have dried up．[精析] 事实细节题[考频：51]。原文首段在讲述沙漠化严重时列举了“地下水源储备下降、河流系统已经干洞”，由此可以推知，B)“供水的短缺”为正确答案。[避错] A)“森林覆盖率的减少”在原文没有涉及，排除；原文虽提及“几十万亩以前灌溉了的粮田已经布满杂草，任风吹拂，无人过问”，但是没有提到“粮食迅速减产”，排除C)；文中abandoned to weeds(布满杂草)并不是说改变成grassland(草地)，属理解错误，排除D)。
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