[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?

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.

thank you. 没有看仔细，唉

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！

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。

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.

Why is A not correct?

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