请教PREP2-48

48.   (33231-!-item-!-188;#058&007563)

Certain messenger molecules fight damage to the lungs from noxious air by telling the muscle cells encircling the lungs' airways to contract.  This partially seals off the lungs.  An asthma attack occurs when the messenger molecules are activated unnecessarily, in response to harmless things like pollen or household dust.

Which of the following, if true, points to the most serious flaw of a plan to develop a medication that would prevent asthma attacks by blocking receipt of any messages sent by the messenger molecules referred to above?

(A) Researchers do not yet know how the body produces the messenger molecules that trigger asthma attacks.

(B) Researchers do not yet know what makes one person's messenger molecules more easily activated than another's.

(C) Such a medication would not become available for several years, because of long lead times in both development and manufacture.

(D) Such a medication would be unable to distinguish between messages triggered by pollen and household dust and messages triggered by noxious air.

(E) Such a medication would be a preventative only and would be unable to alleviate an asthma attack once it had started.

答案是D，我选了E。其实我每怎么看懂原文的意思，虽然我感觉D是对的，因为描述的东西跟原文很相关，但我觉得题干不是说这种药会阻碍任何信息的接收么（a medication that would prevent asthma attacks by blocking receipt of any messages sent by the messenger molecules），那么D选项说这种药不能区分信息又有怎么用呢？？反正就是看不明白。还望大牛们指教！

这道题的意思是：messenger molecules通过。。。来部分封闭肺部来抵御有害空气对肺的伤害。哮喘（asthma）就是这种messenger molecules没必要的过于活跃了，即使遇到花粉或者室内灰尘等无害的也封闭肺部。问题是现在有个计划发明一种治疗哮喘的药，机理是通过拒绝接受所有messenger molecules发出的信号来预防哮喘。问这样有什么缺陷。D的意思是这样一种要无法识别那些信号究竟是由花粉或者室内灰引起来的还是由真正的有害空气引起来的。因为如果这种药不加识别的将所有messenger molecules发出的信号都统统不接受，确实不会哮喘了，但是对有害空气的抵御能力也会全部消失。这样不管真实原因如何一律统一消灭当然是个缺陷了。E说的是这个要只能预防不能再哮喘发作后再发挥效用。这个完全是个无关选项。

谢谢你的解释。关键我就是没看懂题。现在明白了