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标题: GMAT-24-15请教求解思路 [打印本页]

作者: sv2000 时间: 2005-11-11 14:30
标题: GMAT-24-15请教求解思路

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?

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.

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

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.

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.

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.

作者: yangsh 时间: 2005-11-11 16:01
D

作者: williamweizh 时间: 2005-11-12 03:57

该题推理为:

前提: CYSTIC FIBROSES(胆囊纤维化)的肺不能战胜细菌,尽管有同样数量的抗生素,而正好这些人的肺部盐浓度比叫高

结论:盐浓度高的环境抗生素作用降低

怎样UNDERMINE结论呢呢?

一种可能:其他盐浓度高的地方抗生素作用没有降低

第二种可能:盐浓度低的时候抗生素还是没有没有作用.

答案D

ETS一般出题都是第2种思路,即某种事物多/大/浓/推出什么结论,然后题目是WEAKEN,这时候大多答案就是该事物少/小/淡的时候结论不变.

我才复习了1-2星期,了解不多, 欢迎指正!

作者: 不知不觉 时间: 2005-11-12 11:55

以下是引用williamweizh在2005-11-12 3:57:00的发言：

我才复习了1-2星期,了解不多, 欢迎指正!

八过水平挺高的

作者: sv2000 时间: 2005-11-12 13:48
谢谢3楼的解释

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