问两道类似的逻辑

claire_hu

在看Prep逻辑笔记，有两道题目看了答案还有有些迷惑，似乎两题逻辑上有些类似。求赐教。

95.  

Whichof the following most logically completes the passage?

Usingnew detection techniques, researchers have found trace amounts of variousmedicinal substances in lakes and rivers. Taken in large quantities, these substances could have serious healtheffects, but they are present in quantities far too low to cause anyphysiological response in people who drink the water or bathe in it.  Nevertheless, medical experts contend thateliminating these trace amounts from the water will have public healthbenefits, since __________.

A.some of the medicinal substances found in lakes and rivers are harmless tohumans even if taken in large quantities

B.some of the medicinal substances found in lakes and rivers can counteractpossible harmful effects of other such substances found there

C.people who develop undesirable side effects when being treated with medicinesthat contain these substances generally have their treatment changed

D.most medicinal substances that reach lakes or rivers rapidly break down intoharmless substances

E.disease-causing bacteria exposed to low concentrations of certain medicinalsubstances can become resistant to them

答案是E。但是不理解为什么C不可以。由少量有害物质引起的side effect为何不能作为判断依据？解释中提到：该选项也涉及了原文前提中“副作用”一项，不过是副作用产生的另外一种情况，不是“因”的干扰因素。但为何E中“病毒产生抗体”就可以算干扰因素呢？

122.

Untilnow, only injectable vaccines against influenza have been available.  Parents are reluctant to subject children tothe pain of injections, but adults, who are at risk of serious complicationsfrom influenza, are commonly vaccinated. A new influenza vaccine, administered painlessly in a nasal spray, iseffective for children.  However, sincechildren seldom develop serious complications from influenza, no significantpublic health benefit would result from widespread vaccination of childrenusing the nasal spray.

Whichof the following is an assumption on which the argument depends?

A.Any person who has received the injectable vaccine can safely receive thenasal-spray vaccine as well.

B.The new vaccine uses the same mechanism to ward off influenza as injectablevaccines do.

C.The injectable vaccine is affordable for all adults.

D.Adults do not contract influenza primarily from children who have influenza.

E.The nasal spray vaccine is not effective when administered to adults.

这题也是同样的疑问。答案是C。答案E中，成人若也可以用nasal spray，则对public health有benefit。解释中提到：该选项涉及“果”中鼻喷雾器的效果，不能评估因果推理。
如何判断答案能否评估因果推断呢？

看多了脑子有点浆糊。。。求理清思路。。。在此谢过。

ybonne

122 答案是D

claire_hu

ybonne 发表于 2015-1-23 18:40
122 答案是D

打错了，汗。。。为什么呢。。。

elenaknight

因果其实是最好懂的一项。你就看死结论。就像第122题，结论说对public health没什么影响，那你就从选项中找对public health 有影响的就行。D明显是有影响的取非（因为要求assumption).