[求助]GWD24－15

查过了，这题找不到讨论链接。

GWD-24-15.

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.

我觉得,题目说的是:科学家假设high salt environments 要影响其effect

D说就算不是high salt environments,还是不行

所以就削弱了~~