托福阅读：TPO2(Desert Formation)原文及答案

　　11. It can be inferred from the passage that the author most likely believes which of the following about the future of desertification? (Inference Question)

　　A.Governments will act quickly to control further desertification.

　　B.The factors influencing desertification occur in cycles and will change in the future.

　　C.Desertification will continue to increase.

　　D.Desertification will soon occur in all areas of the world.

　　相关原句：

　　The deserts, which already occupy approximately a fourth of the Earth's land surface, have in recent decades been increasing at an alarming pace. It has been estimated that an additional one-fourth of the Earth's land surface is threatened by this process.

　　Once the soil has been removed by erosion, only the passage of centuries or millennia will enable new soil to form. In areas where considerable soil still remains, though, a rigorously enforced program of land protection and cover-crop planting may make it possible to reverse the present deterioration of the surface.

　　本题解析：

　　本题较难，需联系首尾两段。文章开篇便指出沙漠已经(already)覆盖地球四分之一的面积，并且近年来沙漠化以惊人速度扩张(at an alarming pace)，使得又一四分之一的土地(an additional one-fourth of the Earth's land surface)面临威胁。文章结尾时总结到：土壤一旦被腐蚀，只有数百甚至千年后(only the passage of centuries or millennia)才能新生; though理解为“虽然”，作者意图说明虽然在那些土壤尚存的地方通过保护可能(may make it possible to reverse)可以制止恶化，但其实这句话还有言外之意，即那些已经腐蚀严重的地区前景就很不乐观了。综上，作者对沙漠化前景持悲观态度，认为沙化会继续扩张。因此选择C。

　　正确答案：

　　C

　　12. Look at the four squares [■] that indicate where the following sentence can be added to the passage. (Insert Text Question)

　　This economic reliance on livestock in certain regions makes large tracts of land susceptible to overgrazing.

　　Where would the sentence best fit?

　　■(A)The raising of livestock is a major economic activity in semiarid lands, where grasses are generally the dominant type of natural vegetation. This economic reliance on livestock in certain regions makes large tracts of land susceptible to overgrazing. (B) ■The consequences of an excessive number of livestock grazing in an area are the reduction of the vegetation cover and the trampling and pulverization of the soil. (C)■This is usually followed by the drying of the soil and accelerated erosion.(D)■ (Paragraph 7)

　　本题解析：

　　插入句中“economic reliance”对应上句“economic activity,certain regions”对应上句“semiarid lands”,“overgrazing”对应下句“The consequences of an excessive number of livestock grazing”。因此插入句应放在第一句与第三句之间，选择B。

　　正确答案：

　　B

　　13-14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some answer choices do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. (Prose Summary Question)

　　Many factors have contributed to the great increase in desertification in recent decades.

　　●

　　●

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　　Answer Choices

　　1. Growing human populations and the agricultural demands that come with such growth have upset the ecological balance in some areas and led to the spread of deserts.

　　2. As periods of severe dryness have become more common, failures of a number of different crops have increased.

　　3. Excessive numbers of cattle and the need for firewood for fuel have reduced grasses and trees, leaving the land uNPRotected and vulnerable.

　　4. Extensive irrigation with poor drainage brings salt to the surface of the soil, a process that reduces water and air absorption.

　　5. Animal dung enriches the soil by providing nutrients for plant growth.

　　6. Grasses are generally the dominant type of natural vegetation in semiarid lands.

　　本题解析：

　　正确答案应陈述文章主要内容----导致土壤沙漠化近年来迅速扩张的原因。

　　1. 第五、六段指出人口激增和相应的食物需求导致了生态失衡，从而促进沙化恶化。“Expanding populations are subjecting the land to increasing pressures to provide them with food and fuel. ”1正确。

　　2.迷惑选项。文章指出气候干旱是土壤沙化严重的原因之一，但并未说明气候干旱化导致作物种植失败。2错误。

　　3.第七、八段指出过度放牧和燃料收集是沙化继续恶化的原因。

　　“The consequences of an excessive number of livestock grazing in an area are the reduction of the vegetation cover and the trampling and pulverization of the soil. ”

　　“The increased pressures of expanding populations have led to the removal of woody plants so that many cities and towns are surrounded by large areas completely lacking in trees and shrubs. ”

　　3正确。

　　4.第九段指出过度灌溉导致土壤盐化，进而沙漠化。“Excess water from irrigation sinks down into the water table.

　　If no drainage system exists, the water table rises, bringing dissolved salts to the surface.The water evaporates and the salts are left behind, creating

　　a white crustal layer that prevents air and water from reaching the underlying soil. ”4正确。

　　5.可从文章中推出动物粪便对土壤有积极作用。“The increasing use of dried animal waste as a substitute fuel has also hurt the soil because this valuable soil conditioner and source of plant nutrients is no longer being returned to the land.”

　　但注意单纯的谈及动物粪便的作用并非导致沙化的原因，将动物粪便作为燃料从而使土壤缺乏养料来源才是正确原因，5错误。

　　6.细节信息，并非沙化原因，6错误。

　　因此选择134。

　　正确答案：

　　1,3,4