作者：英吉
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.
题目分析：A说当健康的人盐的浓度被人为提高的时候，盐的浓度马上回到正常，说的意思就是你人工提高我也会回来，原文没说，杀。B说有一个样本抗体可以在盐浓度比较低的情况下杀死病菌，说的好像是低盐能是抗体有效，而原文说的是高盐导致抗体无效，没说低盐是否能是抗体有效，范围不对，别发散，杀。C说当盐浓度正常的时候，这个组织能抵抗细菌，和原文有点关系，留着。D说用什么方式治疗这种病，没说，杀。E说高盐浓度在很多情况下使抗体有效，和原文完全相反，无法支持。
