[求助]请教OG-104

原题：

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%.
(C) Had the 1981 tax credit been set higher than 25%, business spending for research and development after 1981 would have increased more than it did.
(D) In the absence of the 25% 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 investments are rarely effective in inducing businesses to make those investments.

答案：

The conclusion that the tax credit did nothing to stimulate spending on research and development would not be true if, without the credit, such spending would have been even lower than it actually was. Thus choice D must be true for the conclusion to be true and is the best answer.

但是，

(D) In the absence of the 25% tax credit, business spending for research and development after 1981 would not have been substantially lower than it was.

是说没有 25% tax credit 的话，business spending for research and development after 1981 不会更低（请注意划线的not）,和答案中的 without the credit, such spending would have been even lower than it actually was 意思刚好相反呀。请各位大牛指点。

谢谢！

不是大牛,但就你的问题而言,你好像没读懂og解释的句子含义.

OG解释:The conclusion that the tax credit did nothing to stimulate spending on research and development would not be true if, without the credit, such spending would have been even lower than it actually was.

简化为: The conclusion would not be true if such spending would have been even lower than it actually was.

意思是: 如果没有这个退税政策,研发费用就会低于实际投入的这种情况成立的话,结论就不成立了.

供参考.

Thanks to lxy128, 不过我的问题不在OG的解释。og解释的句子含义，正如你翻译的一样。“如果没有这个退税政策,研发费用就会低于实际投入。”

然而，D选项

In the absence of the 25% tax credit, business spending for research and development after 1981 would not have been substantially lower than it was.

我理解是：如果没有这个退税政策,研发费用不会低于实际投入。

这与og的解释正好相反呀。我认为应该从D选项中删掉not.

请指教。

兄弟啊,解决这道题的方法套用我这句话是最配的了.

我也解答(不)了你的问题(直至)我阅读了PowerScore出版的LSAT Logical Reasoning Bible.

去掉括号内的字就行了.

这种问题叫Conditional Reasoning的The Unless Equation: A cannot be true unless B is true.解决方法就是 A ->B.用在题目里就是,如果税收优惠没有刺激R&D投入,那一定是______.填入正确答案.你看对不对?

UNLESS,WITHOUT,UNTIL都可以套用在这一类题型.

多谢p200002兄提点,我终于弄明白了!

对babyleader版主说抱歉，偶是新人。今后一定多用搜索功能！谢谢。