请教两条逻辑题，谢谢！

floraxycn

1、A researcher discovered that people who have low levels of immune-system activity tend to score much lower on tests of mental health than do people with normal or high immune-system activity. The researcher concluded from this experiment that the immune system protects against mental illness as well as against physical disease.

 The researcher’s conclusion depends on which of the following assumptions?

(A) High immune-system activity protects against mental illness better than normal immune-system activity does.

(B) Mental illness is similar to physical disease in its effects on body system.

(C) People with high immune-system activity cannot develop mental illness.

(D) Mental illness does not cause people’s immune-system activity to decrease.（D）

(E) Psychological treatment of mental illness is not as effective as is medical treatment.

答案是D，但我不确定推理过程。

18.   The value of a product is determined by the ratio of its quality to its price. The higher the value of a product, the better will be its competitive position. Therefore, either increasing the quality or lowering the price of a given product will increase the likelihood that consumer will select that product rather than a competing one.

Which of the following, if true, would most strengthen the conclusion drawn above?

(A) It is possible to increase both the quality and the price of a product without changing its competitive position.
    

(B) For certain segments of the population of consumers, higher-priced brands of some product lines are preferred to the lower-priced brands.

(C) Competing products often try to appeal to different segments of the population of consumers.

(D) The competitive position of a product can be affected by such factors as advertising and brand loyalty.（E）

(E) Consumers’ perceptions of the quality of a product are based on the actual quality of the product.

答案是E, A为什么不对呀？

谢谢！

[此贴子已经被作者于2007-2-16 15:05:13编辑过]