这道题是陈向东编的GMAT逻辑推理 书中的，因为找不到有关这本书中题目的讨论，所以新开一贴，麻烦nn们帮忙解释下。

P503 

10. A recent survey showed that 50 percent of people polled believe that elected officials should resign if indicted for a crime, whereas 35 percent believe that elected officials should resign only if they are convicted of  a crime. Therefore, more people believe that elected officials should resign if indicted than believe that they should resign if convicted.

The reasoning above is flawed because it

A. draws a conclusion about the population in general based only o a sample of that population

B. confuses a sufficient condition with a required condition

C. is based on an ambiguity of one of its terms

D. draws a conclusion about a specific belief based on responses to queries about two different specific beliefs

E. contains permises that cannot all be true

答案是b, 我选了a

实在想不通b所谓的充分条件，必要条件是怎么对应文中的推理？

怎么没人回复阿？

是不是这本书里面的题目没有意义啊？

NN们请指教一下吧。

indicted for a crime（被起诉）是be convicted a crime（被定罪）的必要条件。一定是先被起诉，再被定罪。所以原文有问题。前提是35%认为官员应该辞职ONLY IF他们被定罪，到了结论ONLY IF没了，那么，认为被定罪该辞职的人，就应该是50％＋35％＝85％，因为认为起诉就该辞职的人，当然认为被定罪的该辞职。那么，实际结论应该与原文结论相反。

所以，原文混淆了充分与必要条件，将indicted与convicted两者的推导顺序弄反了，才会得出那样的结果。

谢谢楼上阿。

一下子明白了。