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标题: [求助]gwd-5-26 [打印本页]
作者: girdle    时间: 2004-9-17 23:07
标题: [求助]gwd-5-26

Q26:


Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces.  eople with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic.  The fluid on a0.irway surfaces in the lungs of people with cystic fibrosis has an abnormally high salt concentration; accordingly, scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.






Which of the following, if true, most strongly supports the scientists’ hypothesis?






  1. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon returns to normal.

  2. A sample of the antibiotic was capable of killing bacteria in an environment with an unusually low concentration of salt.

  3. When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.

  4. Many lung infections can be treated by applying synthetic antibiotics to the airway surfaces.  

  5. High salt concentrations have an antibiotic effect in many circumstances.

answer : c


why b is incorrect?


作者: robertchu    时间: 2004-9-18 13:49

The hypothesis is about the effects of high salt concentration vs. normal salt concentration.  B talks about "an unusually low concentration of salt", and therefore is irrelevant.

作者: girdle    时间: 2004-9-18 15:20

thank you. 没有看仔细，唉

作者: horsefish    时间: 2004-9-18 23:46
以下是引用girdle在2004-9-17 23:07:00的发言：

Q26:


Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces.  eople with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic.  The fluid on a0.irway surfaces in the lungs of people with cystic fibrosis has an abnormally high salt concentration; accordingly, scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.






Which of the following, if true, most strongly supports the scientists’ hypothesis?






  1. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon returns to normal.

  2. A sample of the antibiotic was capable of killing bacteria in an environment with an unusually low concentration of salt.如果把an unusually low concentration改为normal concentration of salt,是B好还是C好?

  3. When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.

  4. Many lung infections can be treated by applying synthetic antibiotics to the airway surfaces.  

  5. High salt concentrations have an antibiotic effect in many circumstances.

answer : c


why b is incorrect?


作者: girdle    时间: 2004-9-19 00:47

我认为还是c 好，我今天也有想过a sample 是否有代表性，是否有可能是偶然

还要请nn指点！

作者: lawyer_1    时间: 2004-9-19 01:09

我认为都一样。因为都是通过浓度降到NORMAL便有杀菌作用来SUPPORT高浓度便不起杀菌作用。

作者: robertchu    时间: 2004-9-19 02:16
以下是引用horsefish在2004-9-18 23:46:00的发言：




IMO, unlike in GMAT Grammar, generally it's probably not a good way of practicing to try "what-if" changes on answer choices in GMAT CR.  It unnecessarily complicate sometimes already complicated questions, and may even cause more confusion at times.


作者: horsefish    时间: 2004-9-19 06:41
以下是引用robertchu在2004-9-19 2:16:00的发言：


IMO, unlike in GMAT Grammar, generally it's probably not a good way of practicing to try "what-if" changes on answer choices in GMAT CR.  It unnecessarily complicate sometimes already complicated questions, and may even cause more confusion at times.





谢谢提醒!


很多时候我竟然分不出来我是做阅读还是做逻辑, 它们实在态象了, 读某句话时我又情不自禁地看有没有语法错误.

作者: brie    时间: 2004-10-17 14:39

Why is A not correct?

作者: bobomomo    时间: 2004-11-8 17:51

觉得A 是在胡说一气 没任何意义 ----- A 就在说什么 把健康的人的盐的浓度人工的提高，然后浓度又自己降到了正常水平 -------  说的东西多文章结论没任何作用 还用那么复杂的语言 让人读好半天 真是讨厌

作者: ethyl    时间: 2005-5-18 04:54

A：无关。没有将浓度与抗菌性结合；可能支持的是健康人可以自我恢复

B：错误比较。文中没有提到低浓度的情况；而且a sample没有代表性

C：事实型加强

D：Many lung infections can be treated，无关

E：太笼统，没有提供有效信息

作者: bigbill    时间: 2005-5-22 09:02
確實  C比B好的多多~~
作者: carmenleaf    时间: 2005-9-5 17:04
以下是引用girdle在2004-9-17 23:07:00的发言：

Q26:


Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces.  eople with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic.  The fluid on a0.irway surfaces in the lungs of people with cystic fibrosis has an abnormally high salt concentration; accordingly, scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.







Which of the following, if true, most strongly supports the scientists’ hypothesis?






  1. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon returns to normal.

  2. A sample of the antibiotic was capable of killing bacteria in an environment with an unusually low concentration of salt.

  3. When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.

  4. Many lung infections can be treated by applying synthetic antibiotics to the airway surfaces.  

  5. High salt concentrations have an antibiotic effect in many circumstances.

answer : c


why b is incorrect?



有一个问题困扰我很久，借此题问一下各位：

结论：scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.

即：high salt concentration ——〉antibiotic ineffective.

那么与之等价的逆否命题则是：antibiotic effective.——〉normal salt concentration

而c选项：a normal salt concentration——〉tissue can resist bacteria则是原命题的否命题，与原命题不等价的呀，所以我坐看右看觉得都不对，不晓得是哪个地方分析错了。

   记得在上XDF的时候把费费给问郁闷了，没好意思再问，结果到现在还是不懂，麻烦大家指点一下呀

作者: ayang1017    时间: 2005-9-25 16:15

建议你看看陈向东那本逻辑，或者也许这个版面谁总结得也有吧。没错逆否是原命题得等价。但是在gmat里所考到得支持，并不需要是充分必要条件，他只需要这个条件得特点是增加了它结论更强，但增加它并不导致结论必然正确～我个人理解

作者: tobytao    时间: 2005-11-14 17:40

哎，我觉得C还是没啥道理，没道理说normal浓度时候antibiotic不起作用一定就能引出说high浓度antibiotic也不起作用啊。。


完全可以认为high浓度的时候antibiotic又发挥作用了啊。。这之间没有positive的关系的吧。。


郁闷啊。。哪位NN解释一下呢？


[此贴子已经被作者于2005-11-14 17:41:44编辑过]
作者: 乌龙茶    时间: 2005-12-19 11:53

我觉得A比较靠谱。


通过antibiotic ineffective 反映出 high salt concentration


侧面事实支持作者hypothesis

作者: cdsteven517    时间: 2006-3-29 18:09
B 是武官选项嘛，CPA 很有用的。。。
作者: eaststar    时间: 2006-5-19 22:45

如果没有C,我认为B也可以选。

作者: yhlin    时间: 2006-7-23 16:01

这题选A

A选项说"salt concentration of the fluid on the airway surfaces of healthy people"提高后，会被回到正常的准位，代表”healthy people”需要正常盐浓度，支持了题目的结论。

反观C只说明在正常浓度，能抵抗细菌，无法支持结论”高浓度会造成antibiotic

失效"

作者: ecochem    时间: 2006-9-24 02:30
以下是引用carmenleaf在2005-9-5 17:04:00的发言：

有一个问题困扰我很久，借此题问一下各位：

结论：scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective.

即：high salt concentration ——〉antibiotic ineffective.

那么与之等价的逆否命题则是：antibiotic effective.——〉normal salt concentration

而c选项：a normal salt concentration——〉tissue can resist bacteria则是原命题的否命题，与原命题不等价的呀，所以我坐看右看觉得都不对，不晓得是哪个地方分析错了。

   记得在上XDF的时候把费费给问郁闷了，没好意思再问，结果到现在还是不懂，麻烦大家指点一下呀

我觉得本题不是must be true题型，正确答案往往就是原论证结论的逆否命题

本题是support的题型，只要提供的信息能够支持结论就行，C选项support了结论。

如果选项中有逆否命题，我倒不觉得一定会是正确答案，因为逆否命题的信息，原文已经给出，此选项并没有提供更多的信息来support结论

一点拙见，欢迎讨论

作者: cattsky    时间: 2006-10-3 15:47

最早选B,现在想想还是C更加有说服力.

且不谈B里的unusally low salt 是不是相关.

B里只讲了一个sample而C里涉及了在单一变量下的对比,变化;证明了salt的作用.

像极了中学里的化学试验:先看看没有加温前的**是什么样子;再看看加温后的**是什么样子;这样对比的结果比单一的高温时的**的样子更有说服力.

另外,normal saltVS high salt,而非low salt VS high salt的论断实在太经典了

作者: tokyolove    时间: 2006-10-19 20:37

此题目c其实是很牵强的。。。

因为在normal的情况，可以退出，肺组织可以起作用 ---------不一定会支持 ，在higher的情况，肺组织不能起作用。 因为，另一种可能是在higer的情况下 ，肺组织也是起作用的！

而B，则说明在浓度极低的情况，肺组织才会起作用。用这种较为极端的比较 则可能会说明 在higher的情况下，肺组织是不起作用的！

作者: 紫丁香花    时间: 2006-10-30 22:20

B: a sample of the antibiotic .../fails to indicate that is it the same "natural antibiotic" mentioned in the artical

C: ..lung tissue(produce normal amounts of the antibiotic)....,the tissue can resist bacteria. /means that the antibiotic produced by the lung tissue can work effectively in a normal salt solution

So,I think C is better.

little opinion, to be disscussed 

作者: best_vivien    时间: 2007-7-11 15:55
以下是引用cattsky在2006-10-3 15:47:00的发言：

最早选B,现在想想还是C更加有说服力.

且不谈B里的unusally low salt 是不是相关.

B里只讲了一个sample而C里涉及了在单一变量下的对比,变化;证明了salt的作用.

像极了中学里的化学试验:先看看没有加温前的**是什么样子;再看看加温后的**是什么样子;这样对比的结果比单一的高温时的**的样子更有说服力.

另外,normal saltVS high salt,而非low salt VS high salt的论断实在太经典了

正解!把我想说的话都说了,哈哈~~

补充下,B的选项只说了在低浓度的时候怎样,可是没有说明这个现象就是因为浓度低产生的,完全可能是其他原因作用的结果.

而C比较了同一事物变化前后的不同,恰恰说明了这个变化才是原因,也就是cattsky所说的单一变量下的对比.

作者: нандин    时间: 2007-8-14 21:40
an unusually low concentration of salt就决定了b的错误.
作者: andylouis    时间: 2007-9-17 19:39
up
作者: rpch2004    时间: 2008-5-29 09:30
以下是引用ecochem在2006-9-24 2:30:00的发言：

我觉得本题不是must be true题型，正确答案往往就是原论证结论的逆否命题

本题是support的题型，只要提供的信息能够支持结论就行，C选项support了结论。

如果选项中有逆否命题，我倒不觉得一定会是正确答案，因为逆否命题的信息，原文已经给出，此选项并没有提供更多的信息来support结论

一点拙见，欢迎讨论

严重同意以上观点：逆否命题多半出现在Must be sure\conclusion题里头，即原文：A->B，正确答案：非B->非A

而支持中，一种常见的方法是无因无果：即原文：A->B，正确答案：非A->非B

例如本题：高浓度->抗生素无效，那么无因无果就是：正常浓度->抗生素有效

作者: happycg    时间: 2008-5-30 09:05
ddddddddddddddddd
作者: Zspirit    时间: 2008-8-3 22:15

做这道题基本按照高考生物的思路做的～
做生物学实验有个变量唯一原则，就是只改变一个要素，看会对结果起什么样的影响。
文章涉及的变量有lung, antibiotic, cystic fibrosis和salt concentration。根据变量唯一原则，要改变salt concentration， 其他因素就必须不变，所以只有C选项其他三项都存在（虽然没有直接说有antibiotic，但是有lung就有antibiotic）
如果没有这个背景，做这题可能会有点困难

作者: flowerfish    时间: 2008-8-29 22:32
终于明白了，其实很多时候是能够看懂的，就是脑子发闷了，谢谢各位指点。
作者: rhine521    时间: 2008-9-6 20:52
和 看到logo 会多给tips的题目属于同一类型
作者: ryanyong    时间: 2009-7-10 09:31

A. When the salt concentration of the fluid on the airway surfaces of healthy people is raised artificially, the salt concentration soon
returns to normal.

盐度被人为提高后悔回复到正常态

B.A sample of the antibiotic was capable of killing bacteria in an environment with an unusually low concentration of salt. 

抗生素在低盐度下可以正常杀菌——和盐度高导致不能杀菌没有关系，因为不能证明抗生素在高盐度下不能杀菌。

C.When lung tissue from people with cystic fibrosis is maintained in a solution with a normal salt concentration, the tissue can resist bacteria.

有CF的肝组织在正常盐度下可以杀菌.

我晕死，我怎么在做题的时候就没有注意到那个“with cystic fibrosis”呢………………


[此贴子已经被作者于2009-7-10 9:34:07编辑过]
作者: adai    时间: 2009-10-10 02:03

我选的是A。A的问题是只说了液体的salt concentration变化，没有说变化与抗体killing harmful bacteria 之间的关系，所以A不如C好；但A的优势在于明确指出了是事发地点是airway

当然C也有道理，但C答案多少也有些问题了 。

尽管题干很明确的说airway是lung的一部分了，即”The fluid on airway surfaces in the lungs“

但是题干又说的是"killing harmful bacteria on airway surfaces"，事发地点是在lung上的airway

C答案说的是“lung tissue can resist bacteria”

这个tissue一定是airway上取的吗，因为液体的salt concentration对airway 上的抗体的工作有影响，对lung的其他部分则不知道了。

综合考虑，还是答案C最好

欢迎讨论...

作者: cheungwenhao    时间: 2013-8-21 18:46
carmenleaf 发表于 2005-9-5 17:04
以下是引用girdle在2004-9-17 23:07:00的发言：Q26:Healthy lungs produce a natural antibiotic that prot ...

这个是 陈向东里面最讨厌的一点，就是说你B，A模式和A，B模式的顺序搞错了，所以会造成你那个B，A之间的错误，以下解释：

scientists hypothesize that the high salt concentration is what makes the antibiotic ineffective
这个是典型的B，A型； 盐高A是抗体没有用B的一个必要条件，逻辑图表示：B——〉A（这里很多人都错！）

那样很简单就能够知道C选项就是逆否命题了！现在看黄砖的人少了，陈向东老师的逻辑系统很严密的，不过考场考的还是做题，不是分析题目，所以没有什么多大道理，直接无关：你卖蔬菜的，回答我买bra的价格，这个不好玩！狒狒怎么会给你问蒙呢?
作者: zzloveyibo    时间: 2014-3-13 12:45
个人觉得应该是C更好



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