文勇的新托福黄金&ccedil

beeninterpretedbysomeasasignthatmagicalreligiousactiv

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Unformatted text preview: tion against plant­eating insects and microbial pathogens. 8. Why does the author mention herbs, shrubs, and trees? To provide examples of plant types that cannot tolerate high levels of harmful minerals. To show why so many plants are hyper accumulators. To help explain why hyper accumulators can be found in so many different places. To emphasize that hyper accumulators occur in a wide range of plant types. 9. The word afford in the passage is closest in meaning to offer prevent 183 Mail@liuwenyong.com 在在在在在在 www.liuwenyong.com 在在在在在在在在在在在在在在在,在在在在在在在在在在 increase remove Paragraph 6: Only recently have investigators considered using these plants to clean up soil and waste sites that have been contaminated by toxic levels of heavy metals – an environmentally friendly approach known as phytoremediation. This scenario begins with the planting of hyper accumulating species in the target area, such as an abandoned mine or an irrigation pond contaminated by runoff. Toxic minerals would first be absorbed by roots but later relocated to the stem and leaves. A harvest of the shoots would remove the toxic compounds off site to be burned or composted to recover the metal for industrial uses. After several years of cultivation and harvest, the site would be restored at a cost much lower than the price of excavation and reburial, the standard practice for remediation of contaminated soils. For examples, in field trials, the plant alpine pennycress removed zinc and cadmium from soils near a zinc smelter, and Indian mustard, native to Pakistan and India, has been effective in reducing levels of selenium salts by 50 percent in contaminated soils. 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. Before considering phytoremediation, hyper accumulating species of plants local to the target area must be identified. The investigation begins with an evaluation of toxic sites in the target area to determine the extent of contamination. The first step in phytoremediation is the planting of hyper accumulating plants in the area to be cleaned up. Mines and irrigation ponds can be kept from becoming contaminated by planting hyper accumulating species in targeted areas. 11. It can be inferred from Paragraph6 that compared with standard practices for remediation of contaminated soils, phytoremediation does not allow for the use of the removed minerals for industrial purposes. can be faster to implement is equally friendly to the environment is less suitable for soils that need to be used within a short period of time. 12. Why does the author mention Indian mustard? To warn about possible risks involved in phytoremediation To help illustrate the potential of phytoremediation To show that hyper accumulating plants grow in many regions of the world To explain how zinc contamination can be reduced. Paragraph5: Scientists have known for some time that certain plan...
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This note was uploaded on 09/17/2013 for the course LANGUAGE 13DL208 taught by Professor Wang during the Fall '13 term at East China Normal University.

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