托福阅读修辞目的题是阅读考试中比较常见的一种题型，tpo则是托福阅读备考最权威的材料 ，所以托福小编综合二者，为大家集中整理了tpo阅读中考察的修辞目的题及其对应的解析，供大家参考使用。本文带来的是TPO5-1的修辞目的题，一起来看看吧。
TPO5-1 Minerals and Plants
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Scientists have known for some time that certain plants, called hyper accumulators, can concentrate minerals at levels a hundredfold or greater than normal. ■ A survey of known hyper accumulators identified that 75 percent of them amassed nickel, cobalt, copper, zinc, manganese, lead, and cadmium are other minerals of choice. ■Hyper accumulators run the entire range of the plant world. ■ They may be herbs, shrubs, or trees. ■ Many members of the mustard family, spurge family, legume family, and grass family are top hyper accumulators. Many are found in tropical and subtropical areas of the world, where accumulation of high concentrations of metals may afford some protection against plant-eating 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.
解析：修辞目的题，而且这句话中有个they，指代前文，所以往前看，说HA在整个植物界分布广泛，后面的几种植物就是HA的例子，所以答案是D。A说cannot tolerate反了;原文没说到原因，所以B/C都错
[5]科学家早前就了解到，某些所谓的富集植物能够比普通植物多集中100倍甚至更多的矿物质。一项对已知富集植物的调查表明，它们中75%积聚了镍，而钴、铜、锌、锰、铅和镉则是其他选择性聚集的矿物质。富集植物存在于整个世界范围，它们可能是草本植物、灌木或树。芥属、大戟属、豆科和禾本科植物中的许多成员都是靠前的富集植物。许多富集植物被发现于热带和亚热带，金属可以为植物提供保护，对抗植食昆虫和细菌病原体。
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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.
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.
解析：修辞目的题，Indian mustard做关键词定位至最后一句，这句话整个是个例子，而且之前的那句话也是个例子。再往前就是上题的那句话，也就是说经过若干年耕种与收割，那个地方就会变好，也就是这种方法有用，所以答案B正确。
[6]直到最近研究者才考虑用这些植物来清理已经被有毒重金属污染的土壤和废弃物物处理点——一种被称为植物修复法的修复方法。这套方案首先从在目标区域种植超积累物种开始，如在废弃矿井和被径流污染的灌溉池塘。有毒矿物质首先被根吸收，随后被运送至茎和叶。收割下来的枝叶将被焚烧以移除有毒化合物或被制成混合肥料回收金属用于工业。经过几年的种植和收割，该污染点将被修复，而其造价远比修复污染土壤的标准做法——挖掘和填埋来得低。举例来说，在实地试验中，高山菥蓂从靠近一个锌冶炼厂的土壤中去除了锌和镉，原产自巴基斯坦和印度的印度芥菜可以将染土壤中硒的水平有效地降低了50%。
以上就是托福阅读TPO5-1中的修辞目的题及其解析，大家可以在备考的时候参考复习，希望能够帮助大家的考前准备。最后前程百利祝大家都能取得理想的托福考试成绩。
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