托福阅读：TPO2(Desert Formation)原文及答案

　　6. According to paragraph 6, which of the following is often associated with raising crops?(Factual Information Question)

　　A.Lack of proper irrigation techniques

　　B.Failure to plant crops suited to the particular area

　　C.Removal of the original vegetation

　　D.Excessive use of dried animal waste

　　相关原句：

　　Since the raising of most crops necessitates the prior removal of the natural vegetation.( Paragraph 6)

　　本题解析：

　　necessitate意为“使…必须”，即作物种植(raising crops)必须先除掉原有植被(the prior removal of the natural vegetation)，因此选择C。

　　正确答案：

　　C

　　7. The phrase devoid of in the passage is closest in meaning to (Vocabulary Question)

　　A.Consisting of

　　B.Hidden by

　　C.Except for

　　D.Lacking in

　　相关原句：

　　Since the raising of most crops necessitates the prior removal of the natural vegetation, crop failures leave extensive tracts of land devoid of a plant cover and susceptible to wind and water erosion.( Paragraph 6)

　　本题解析：

　　devoid of 意为“缺乏…”，与lacking in同义。本题答案也可从前句推出：前句指出作物种植必须先除掉原有植被，因此可推出作物种植失败将会遗留下大片失去植被的土地，因此选择D。

　　正确答案：

　　D

　　8. According to paragraph 9, the ground’s absorption of excess water is a factor in desertification because it can (Factual Information Question)

　　A.Interfere with the irrigation of land

　　B.Limit the evaporation of water

　　C.Require more absorption of air by the soil

　　D.Bring salts to the surface

　　相关原句：

　　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.( Paragraph 9)

　　本题解析：

　　相关句指出过量灌溉带来的水(excess water from irrigation)渗入地下，如没有排水道，则地下水位上升，将溶解的盐带到土壤表层(bringing dissolved salts to the surface)。因此选择D。

　　正确答案：

　　D

　　9. All of the following are mentioned in the passage as contributing to desertification EXCEPT(Negative Factual Information Question)

　　A.Soil erosion

　　B.Global warming

　　C.Insufficient irrigation

　　D.The raising of livestock

　　相关原句：

　　The final major human cause of desertification is soil salinization resulting from

　　over irrigation.( Paragraph 9)

　　本题解析：

　　段落首句指出过渡灌溉(over irrigation)会导致沙漠化，逻辑取非可得出灌溉不足(insufficient irrigation)不是沙化的原因。文章2、4、7段分别说明土壤腐蚀(A .Soil erosion)、全球变暖(B. Global warming)、过度放牧(D. the raising of livestock)导致了沙漠化，排除方法亦可得出答案C。

　　正确答案：

　　C

　　10. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? (Sentence Simplification Question)

　　A.Desertification is a significant problem because it is so hard to reverse and affects large areas of land and great numbers of people.

　　B.Slowing down the process of desertification is difficult because of population growth that has spread over large areas of land.

　　C.The spread of deserts is considered a very serious problem that can be solved only if large numbers of people in various countries are involved in the effort.

　　D.Desertification is extremely hard to reverse unless the population is reduced in the vast areas affected.

　　相关原句：

　　The extreme seriousness of desertification results from the vast areas of land and the tremendous numbers of people affected, as well as from the great difficulty of reversing or even slowing the process.(Paragraph 10,highlighted sentence)

　　本题解析：

　　本句指出沙漠化的严重性主要是由于(result from)：1)波及地区和人口广泛(the vast areas of land and the tremendous numbers of people affected);2)难以逆转的状态(the great difficulty of reversing or even slowing the process)。因此选择A。

　　需注意该句两个“from”表明了两个并列的原因。

　　正确答案：

　　A