由GWD24-15问他因削弱

birgo

首先GWD24-15题是这样的:

Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces. People with cystic fibroses, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic. Since the fluid on airway surfaces in the lungs of people with cystic fibrosis bas an abnormally high salt concentration, scientists hypothesize that in high salt environments the antibiotic becomes ineffective at killing harmful bacteria.

Which of the following, if it were obtained as an experimental result, would most decisively undermine the scientists’ hypothesis?

1. Healthy lungs in which the salt concentration of the airway-surface fluid has been substantially increased are able to reestablish their normal salt concentration within a relatively short period of time.

2. The antibiotic produced by the lungs is effective at killing harmful bacteria even when salt concentrations are below levels typical of healthy lungs.

3. The salt concentration of the airway-surface fluid in the lungs of people who suffer from cystic fibrosis tends to return to its former high levels after having been reduced to levels typical of healthy lungs.

4. The lungs of people who suffer from cystic fibrosis are unable to fight off harmful bacteria even when the salt concentration is reduced to levels typical of healthy lungs.

5. The salt concentration in the airway-surface fluid of people whose lungs produce lower-than-average amounts of the antibiotic is generally much lower than that typical of healthy lungs.

答案是D. 我看了一下,基本上大家的解释都是说属于他因削弱, 即题干说的是high salt导致antibiotic becomes ineffective at killing harmful bacteria, D选项说的是即使在low salt的环境下,antibiotic 仍然无法消灭细菌, 相比其他选项D是最好的, 但是我现在的困惑是D就真的能weaken吗?

举个例子来说, "下雨导致地湿", 但是你是否可以说"天没有下雨,地就湿了"就weaken了"下雨导致地湿"吗?

我不知道是不是我的思路有点问题,想得太复杂了, 请大家帮忙看看吧. 谢谢.

mypiao

  晕没看懂楼主的意思,现在有人怀疑下雨导致了地湿;如果有证据表明,没有下雨,地还是湿地,当然可以反驳掉下雨导致地湿阿.

  生活中很正常地一个思维阿.怀疑一个因素导致某种结果,那就把这个因素去掉,看看是不是还会发生同样地结果.我认为我太胖了,所以泡不到妞.结果我减肥成功后,还是发现自己泡不到妞,显然说明不是因为胖,我才泡不到妞地( 太丑 or 太穷??) 

Anyway,希望对lz理清楚思路有帮助.

[此贴子已经被作者于2007-6-15 20:42:57编辑过]

iamhere

文中的意思科学家发现肺病病人的盐浓度比正常人高，所以他们假设是盐浓度过高导致病人的肺不正常

D：患cystic fibrosis的病人，在降低肺里的盐浓度后，仍然unable to fight off harmful bacteria

所以得出结论：盐浓度过高并不是患cystic fibrosis的病人unable to fight off harmful bacteria的原因

s7s7

高盐浓度下，抗体失活

低盐下，还是失活，说明盐浓度无关。

bmwedward

此題與GWD5-26一樣, 在此Po上以供參考

GWD5-Q26:

Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces.  People with cystic fibrosis, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic.  The fluid on airway 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?

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.

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

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

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

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

answer:C

GWD24-15與GWD5-26不同之處就是一個問undermine一個問support

兩題重點都在只要有normal salt concertration 就可以resist bacteria , 不管有沒有cystic fibrosis, 

GWD24-15問undermine時, 答案D寫道

D. The lungs of people who suffer from cystic fibrosis are unable to fight off harmful bacteria even when the salt concentration is reduced to levels typical of healthy lungs.

表示salt concertration 已降到健康的水準但還是不能抵抗細菌, 此表示undermine

小弟淺見, 請多指教!