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GRE阅读题目解析:氟化物抗牙齿腐化

2017-04-13 09:17:00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 4 mg)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，二氧化硫，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 4 mg 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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