OG 12 53 看过前人的，还是不解B

欢乐

Most employees in the computer industry move from company to company, changing jobs several times in theircareers. However, Summit Computers is known throughout the industry for retaining its employees. Summitcredits its success in retaining employees to its informal, nonhierarchical work environment.
Which of the following, if true, most strongly supports Summit’s explanation of its success in retaining employees?

(B) A hierarchical work environment hinders the cooperative exchange of ideas that computer industry
employees consider necessary for their work.

(D) In a nonhierarchical work environment, people avoid behavior that might threaten group harmony and
thus avoid discussing with their colleagues any dissatisfaction they might have with their jobs.
仔细想了一下 关于B
原文可得：
A informal ,nonhierachical environment -> B  success in retaining employment
而B选项：非A 则 B 不成立
就是说 非A->非B 是原文的否命题，而不是逆否命题，不等价。为什么起到了加强的作用呢？不解

请NN不吝赐教

hzyhzygold

关键在于B的necessary,其它选项不对就是因为不necessary。

欢乐

嗯嗯，您给的剖析真够透彻的。太感谢您了。

欢乐

自己想顶一下。就是没想通非A——>非B 命题成立 为什么会加强 A——>B
否命题可相互加强？