新GRE阅读理解36套每日讨论--72（qq群178674184）

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Questions 6 to 8 are based on the following reading
passage.  
   
The success of fluoride in combating dental decay is
well established and, without a doubt, socially beneficial.
However, fluoride's toxic properties have been known for
a century. 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.  
Some important questions remain. For example, the
precise lower limit at which the fluoride content of bone
becomes toxic is still undetermined. 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.  


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

7. One function of the second paragraph 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  


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.

普渡哥

有人做了没？

普渡哥

有人做了吗？快回答案，我出新题啊！！

普渡哥

有谁做了没 ？

韩洋

B D A

普渡哥

正确答案：

6.B 7. D    8. C

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