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. These difficulties suggest that we should by wary of indiscriminately using fluoride, even in the form of fluoride-containing dental products.

 

8. In the passage, the author is primarily concerned with

   (A) analyzing and categorizing

   (B) comparing and contrasting

   (C) synthesizing and predicting

   (D) describing and cautioning

   (E) summarizing and reinterpreting

 

9. 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

 

10. 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

 

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

    (A) The effect is more easily measured than is the effect of exposure to pesticides.

    (B) The effect of fluoride intake from water and air is relatively difficult to monitor.

    (C) In general the effect is not likely to be as harmful as the effect of exposure to sulfur dioxide.

    (D) An intake of 4 milligrams over a long period of time usually leads to a skeletal disorder in humans.

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

 

    Brown's results are clearly consistent with Fuch's argument that discrimination by consumers has a greater impact on the earnings of women than does discrimination by either government or private employers. Also, the fact that women do better working for government than for private employers implies that private employers are discriminating against women. The results do not prove that government does not discriminate against women. They do, however, demonstrate that if government is discriminating against women, its discrimination is not having as much effect on women's earnings as is discrimination in the private sector.

 

第四段

focus:歧视妇女的不同群体

第七题

(A)  无关内容 free market

(B)  错误内容 why