标题: og-104 [打印本页] 作者: sunhx 时间: 2003-11-26 01:25 标题: og-104 Spending on research and development by United States businesses for 1984 showed an increase of about 8 percent over the 1983 level. This increase actually continued a downward trend evident since 1981-when outlays for research and development increased 16.4 percent over 1980 spending. Clearly, the 25 percent tax credit enacted by Congress in 1981, which was intended to promote spending on research and development, did little or nothing to stimulate such spending. The conclusion of the argument above cannot be true unless which of the following is true? A Business spending on research and development is usually directly proportional to business profits. B Business spending for research and development in 1985 could not increase by more than 8.3 percent. C Had the 1981 tax credit been set higher than 25 percent, business spending for research and development after 1981 would have increased more than it did. D In the absence of the 25 percent tax credit, business spending for research and development after 1981 would not have been substantially lower than it was. E Tax credits market for specific inverstments are rarely effective in inducing businesses to make those investments.
答案是D.请帮忙分析一下. 作者: 深海的小美人鱼 时间: 2003-11-26 04:10
D的意思是说没有那25％的退税，花费在研究上的费用也不会少， 正好加强了结论。因为结论是说the 25 percent tax credit enacted by Congress in 1981, which was intended to promote spending on research and development, did little or nothing to stimulate such spending作者: jandj_shanghai 时间: 2003-11-27 08:24
文中说25% tax credit did little or nothing （因为只增长了8%） 考虑这种情况：如果没有这25%，不仅不会增长还会大大减少。那不就说明了这25%换来的8%不是little or nothing了吗。 D排出了这种可能。作者: joywzy 时间: 2003-11-27 08:47
这题是这样的结构：A---》B，假设是没有B----》没有A，是逆否命题，所以对。作者: forjoke 时间: 2005-5-19 13:55
A cannot be true unless B ＝ A －》B B是A的必要条件。 其实就是问从题中的conclusion可以推出什么结论？――D tax credit 没起作用 ＝ 没有那25％的退税，花费在研究上的费用也不会少