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GRE阅读题目解析:氟化物对抗牙齿腐化

2016-12-01 09:58:02来源：网络
　　P3

　　1

　　The success of fluoride in combating dental decay is well established and, without a doubt, socially beneficial.

　　氟化物已经被公认，能够有效对抗牙齿腐化，显然这对整个社会都有益。

　　2

　　However, fluoride's toxic properties have been known for a century.

　　而早在一个世纪以前，氟化物就被发现具有毒性。

　　3

　　In humans excessive intake (for adults, over 4 milligrams per day) over many years can lead to skeletal fluorosis, a well-defined skeletal disorder, and in some plant species, fluoride is more toxic than ozone, sulfur dioxide, or pesticides.

　　人类如果常年过量摄入(对成人来说，每天超过4mg)氟化物会导致氟骨病，一种已经被清晰描述的骨骼异常，对于一些植物种属，氟化物的毒性超过臭氧，氧化硫，或农药。

　　4

　　Some important questions remain.

　　仍有一些重要问题有待回答。

　　5

　　For example, the precise lower limit at which the fluoride content of bone becomes toxic is still undetermined.

　　比如说，骨骼中超过一定比例的氟化物表现出毒性，更精确的临界点仍未测定。

　　//

　　前文说了成人4mg的标准，但现在根据 precise lower limit，我们有理由怀疑 4 mg per day 这个数值不够精确，也许 3.9 已经可以表现出毒性了。

　　//

　　6

　　And while fluoride intake from water and air can be evaluated relatively easily, it is much harder to estimate how much a given population ingests from foodstuffs because of the wide variations in individual eating habits and in fluoride concentrations in foodstuffs.

　　而且，尽管通过水和空气摄取的氟化物的量相对容易估算，但特定人群通过食物摄取的氟化物的数量较难估算，因为每个人的饮食习惯各异，而不同食物中的氟化物浓度也不同。

　　6. The passage suggests that it would be easier to calculate fluoride intake from food if

　　○A adequate diets were available for most people.

　　○B individual eating habits were more uniform

　　○C the fluoride content of food was more varied

　　○D more people were aware of the fluoride content of food

　　○E methods for measuring the fluoride content of food were more generally agreed on

　　选B

　　根据句 6 ：

　　……it is much harder to estimate how much a given population ingests from foodstuffs because of the wide variations in individual eating habits……

　　7. One function of the second paragraph(句4，5，6) of the passage is to

　　○A raise doubts about fluoride's toxicity

　　○B introduce the issue of fluoride's toxicity

　　○C differentiate a toxic from a nontoxic amount of fluoride

　　○D indicate that necessary knowledge of fluoride remains incomplete

　　○E discuss the foodstuffs that are most likely to contain significant concentrations of fluoride

　　选D

　　暗示，关于氟化物的一些必要知识，还有待补充。

　　For the following question, consider each of the choices separately and select all that apply

　　8.The passage suggests which of the following about the effect of fluoride on humans?

　　□A The effect of fluoride intake from water and air is relatively difficult to monitor.

　　□B An intake of 4 milligrams over a long period of time usually leads to a skeletal disorder in humans.

　　□C An intake of slightly more than 4 milligrams for only a few months is not likely to be life-threatening.

　　选C

　　A 错。文章从头到尾都没有讨论过不同途径吸收的氟化物，有什么不同的 effect 。

　　B 错。没有 per day ，如果只是某一天 4mg ，又过了很长一段时间，应该不至于有什么问题。句 3 告诉我们，不但要 per day，而且要 over many years。

　　于是只能选 C。

　　以上就是新东方在线GER频道为你带来的GRE阅读题目解析:氟化物对抗牙齿腐化，更多精彩敬请关注新东方在线GRE频道。

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