解释不清：og-102

zcx

102. Although migraine headaches are believed to be caused by food allergies, putting patients on diets that eliminate those foods to which the patients have been demonstrated to have allergic migraine reactions frequently does not stop headaches. Obviously, some other cause of migraine headaches besides food allergies much exist.

Which of the following, if true, would most weaken the conclusion above?

(A) Many common foods elicit an allergic response only after several days, making it very difficult to observe links between specific foods patients eat and headaches they develop.

  

og的解释：If it is difficult to determine which foods cause migraines, then some foods that cause allergic reactions might not have been demonstrated to do so. Hence, if choice A is true, eliminating foods that have been demonstrated to cause migraines might not eliminate migraines, even if food allergies are the only cause of migraines. Choice A is the best answer.

  

原题：现象：禁食引起过敏的食物仍有头痛。

         结论：还有别的原因导致头痛。

a weaken:事物的过敏反应会延迟出现，所以判断食物与头痛的关系很难。与og 解释出发点不一样的。a实说不出现反应，og实说别的食物可以引起头痛？

睡熊

还是阅读理解的问题。除了那种已被证明引起过敏的食物外，还有其它一些普通的食物也能引起过敏，但由于症状延迟的原因，很难弄清过敏症状和食物的对应关系。这样，即便排除那种已知的食物，由于还存在其它未知的食物也能引起过敏，所以，这种过敏依然是由于食物引起的。并不一定说明存在食物以外的因素。

zcx

好像明白了一点，如果像你说的，这题的weaken方法是不是    非a推不出b, 即说还是国民失误导致的头痛，不是别的原因，只是因为不出现反应而已？

dansy

对，题目是这个意思。不过不明白你说的非A，非B是什么意思？

zcx

这边新东方老师说的冬冬，偶也不太懂，运用起来很慢。

睡熊

如果一定要用逻辑表达的话，此题是否定论据型削弱。即：


原文：a => b


削弱：a 不成立 ~a=1


但此时，b成不成立我们不知道，只是知道原来的论证被削弱了（非否定）。

zcx

gg,你的逻辑很强，怎么学的？看什么书？

睡熊

其实不太好，刚刚做完一遍LSAT，感觉帮助很大。

zcx

gg你是直接就做lsat的题目还是先把gmat的提做完了才转lsat的？没有专门看什么书吗？你觉得逻辑是用意思做题还是方法做题好些？

tony6

此题的D项，VERY FEW不是有否定的意思吗？

Very few patients have allergic migraine reactions as children live migraine-free adult lives once they have eliminated from their diets foods to which they have been demonstrated to be allergic.

如果是“很少人有头疼反应，如果他们不吃会引发过敏的食物的话”，那不还是食物的问题吗？

也就是说还是对最后结论的WEAKEN吗？

[此贴子已经被作者于2004-6-17 21:58:15编辑过]