20. When people predict that certain result will not take place unless a certain action is taken, they believe that they have learned that the prediction is correct when the action is taken and the result occurs. On reflection, however, it often becomes clear that the result admits of more than one interpretation.
Which of the following, if true, best supports the claims above?
(A) Judging the success of an action requires specifying the goal of the action.
(B) Judging which action to take after a prediction is made requires knowing about other actions that have been successful in similar past situations.
(C) Learning whether a certain predictive strategy is good requires knowing the result using that strategy through several trials.
(D) Distinguishing a correct prediction and effective action from an incorrect prediction and ineffective action is often impossible.（D）
(E) Making a successful prediction requires knowing the facts about the context of that prediction.
答案是D, 请问解题思路是什么? 感觉答案象中心思想似的.
谢谢!作者: gmatmba 时间: 2010-12-1 19:59
提一个简单思路，
我觉得这里面有两个元素，Result Action 。其中，Action是个必要条件，两者构成一个Pridiction
用逻辑表示就是： R -> A ，但是人们会误以为使 A -> R，这就是矛盾的根源
用语言表达就是：当人们说如果R不会发生，除非A了；人们会认为A了就R了；但是A了的结果还不一定呢
举一个例子：“我不会去找你，除非你给我暗示”；人们可能会以为“你给我暗示，我就会找你”；但是实际上“你给我暗示”是个必要条件不是充分条件，所以我去不去找你还不一定呢，我可能去找你，也可能不去找你。
综上：就会有文正中最后的结论，结果不唯一。
上面是对题目的分析，看选项D表达了这个意思，因为两种可能性都有，无法区别。所以就选这个了。
只能想到这儿了，还没有完全想通，盼望牛人来点拨！！作者: youngerlee 时间: 2010-12-2 06:41
文章说的是a certain action和result之间的关系，因此the goal of the action（choice A）、which action（choice B）、strategy(choice C)、the context of the prediction（choice E）都无关，可以排除。只有D说的是action和result之间的关系（也就是prediction是否正确），所以D对。
