费费的20、30题

bz

20. a rise in the percentage of all 18-year-olds who were recruited by the armed services of a small republic between 1980 and 1986 correlates with a rise in the percentage of young people who dropped out of high school in that republic. since 18-year-olds in the republic are generally either high school graduates or high school dropouts, the correlation leads to the conclusion that the republic’s recruitment rates for 18-year-olds depend substantially on recruitment rates for high school dropouts.
which one of the following statements, if true, most weakens the argument?
(a) a large number of 18-year-old high school graduates were recruited for the republic’s armed services in 1986 than in 1980.
(b) many of the high-technology systems used by the republic’s armed services can be operated only by individuals who have completed a high school education.
(c) between 1980 and 1986 the percentage of high school graduates among 18-year-olds recruited in the republic rose sharply
(d) personnel of the republic’s armed services are strongly encouraged to finish their high school education.
(e) the proportion of recruits who had completed at least two years of college education was greater in 1986 than in 1980.
费费的答案是c, 哪位大虾解释一下，b为何不行。

30. combustion of gasoline in automobile engines produces benzene, a known carcinogen. environmentalists propose replacing gasoline with methanol, which does not produce significant quantities of benzene when burned. however, combustion of methanol produces formaldehyde, also a know carcinogen. therefore the environmentalists’ proposal has little merit.
which one of the following, if true, most supports the environmentalist’ proposal?
(a) the engines of some automobiles now on the road burn diesel fuel rather than gasoline.
(b) several large research efforts are under way to formulate cleaner-burning types of gasoline.
(c) in some regions, the local economy is largely dependent on industries devoted to the production and distribution of automobile fuel.
(d) formaldehyde is a less potent carcinogen than benzene.
(e) since methanol is water soluble, methanol spills are more damaging to the environment than gasoline spills.
费费选b，e怎么不行？是不是两个答案弄反了？
还有一个问题，费费和最后考是哪个难？ 我快撞墙了！！！！

greenapple

20题抽出来的关系可以表示如下:
  a rise in the percentage of all 18-year-olds who were recruited  ----->either high school graduates or high school dropouts  rise
  而题中的结论肯定了后一半,事实上也有可能是前一半,所以C的反驳力最强.B我觉得是SECOND BEST,但它又引入了新的信息,且前提是军队必然招收能胜任的学生,没有C来得直接.
30题 我查了一下,答案是D.