[求助]og11的这题怎么理解呢？

happypoor88

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 systems.

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

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

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

这题为什么选择D呢？这类ASSUMPTION题没有逻辑链断层，新东方老师说是找出否定任何有可能削弱原文结论的意见，因为原文作者认为自己的推理完全正确，那么D选项取非后应该是Mental illness 会引起immune-system activity 下降，那怎么削弱了原文了呢？

tommytang

这题的conclusion是immune system protects against mental illness as well as against physical disease,根据的事实是immune system低的人在测试mental health中的得分低于正常或高immune system的人，所以这题认为是low immune system导致mental health降低的。对选项D取非后则是mental illness导致immune system下降，和题目中的推理正好因果颠倒，所以是消弱了原文。

happypoor88

哦～～～懂了，因果倒置，十分感谢tommytang，真是好人！

binfenliu

谢谢,这个题,我也挺迷惑.

CShadow

感觉在GMAT很多题目与这题很像。就是在问assumption的题中，题干中A－＞B，而选项中B－＞A，那么一般这个选项就是正确答案了。