大全-D-7

7.     The postal service is badly mismanaged. Forty years ago, first-class letter delivery cost only three cents. Since then, the price has increased nearly tenfold, with an actual decrease in the speed and reliability of service.

Each of the following statements, if true, would tend to weaken the argument above EXCEPT:

(A) The volume of mail handled by the postal service has increased dramatically over the last forty years.

(B) Unprecedented increases in the cost of fuel for trucks and planes have put severe upward pressures on postal delivery costs.

(C) Private delivery services usually charge more than does the postal service for comparable delivery charges.

(D) The average delivery time for a first-class letter four decades ago was actually slightly longer than it is today.（E）

(E) The average level of consumer prices overall has increased more than 300 percent over the last forty years.

虽然E也解释得通，但是C为什么可以weaken the argument?——private delivery service比postal service要价更高，不表示postal service本身没有badly mismanaged啊。  另外，D和原文信息相悖，“with an actual decrease in the speed and reliability of service.”和“was actually slightly longer than it is today”有矛盾。

It is good that you think that way. However, the conclusion of the argument is based on the price increase. With C, the premises in the argument will no longer be as strong to reach the conclusion. Moreover, this is weaken question. We do not have to be sure that the conclusion is false. It only has to be weakened. Therefore C weakens the argument.

As to D, you should read that "if true" in the question. You should then know that D is assumed to be true, not the information provided in the argument. So D counters the information provided by the argument, thus weakening the argument.

这句话不是也同样能用在E上，并不是一定要证明false, weaken就行了。物价水平涨了3倍，虽说不是10倍，但是也weaken了呀。