Fact: Asthma, a bronchial condition, is much less common ailment than hay fever, an allergic inflammation of the nasal passages.
Fact: over 95 percent of people who have asthma also suffer from hay fever.
If the information given as facts above is true, which of the following must also be true?
A. Hay fever is a prerequisite for the development of asthma
B. Asthma is a prerequisite for the development of hay fever
C. Those who have neither hay fever nor asthma comprise less than 5 percent of the total population
D. The number of people who have both of these ailments is greater than the number of people who have only one of them
E. The percentage of people suffering from hay fever who also have asthma is lower than 95 percent.
E why not b? 这种题好难理解啊？
谢谢!
用一下gmat数学里面的集合知识
画个韦恩图一下就出来了
（分子）交集不变
分母增大（ Asthma is much less common ailment than hay fever） 两个集合有大小之分
楼上说的对，这题是个数学问题。
关于B的问题，其实和A一样，都是推不出来的：由原文的信息是无法推出这两种病有任何前提关系。
B假设了因果关系. 是不对的.
非常感谢！
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