托福阅读：TPO2(Desert Formation)原文及答案

　　7. The phrase devoid of in the passage is closest in meaning to

　　Consisting of

　　Hidden by

　　Except for

　　Lacking in

　　Paragraph 9: The final major human cause of desertification is soil salinization resulting from over irrigation. 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.

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

　　Interfere with the irrigation of land

　　Limit the evaporation of water

　　Require more absorption of air by the soil

　　Bring salts to the surface

　　9. All of the following are mentioned in the passage as contributing to desertification EXCEPT

　　Soil erosion

　　Global warming

　　Insufficient irrigation

　　The raising of livestock

　　Paragraph 10: 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. 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.

　　10. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?

　　Incorrect choices change the meaning in important ways or leave out essential information.

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

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

　　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.

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

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

　　Governments will act quickly to control further desertification.

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

　　Desertification will continue to increase.

　　Desertification will soon occur in all areas of the world.

　　Paragraph 7:■ The raising of livestock is a major economic activity in semiarid lands, where grasses are generally the dominant type of natural vegetation. ■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. ■This is usually followed by the drying of the soil and accelerated erosion.■

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

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

　　Where would the sentence best fit?

　　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.

　　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.