逻辑复习从假设题开始,请帮忙分析取非找答案.

准备用一个星期的时间系统的复习一下逻辑.

今天从假设题开始. 

假设题选项取非结论不成立即为正确答案,我不会应用,请大家用这题教我一下.

59. To prevent some conflicts of interest, Congress could prohibit high-level government officials from accepting positions as lobbyists for three years after such officials leave government service. One such official concluded,
            however, that such a prohibition would be unfortunate because it would prevent high-level government officials from earning a livelihood for three years.

The official's conclusion logically depends on which of the following assumptions?

(A)     Laws should not restrict the behavior of former government officials.

(B)     Lobbyists are typically people who have previously been high-level government officials.

(C)    Low-level government officials do not often become lobbyists when they leave government service.

(D)    High-level government officials who leave government service are capable of earning a livelihood only as lobbyists.

(E)  High-level government officials who leave government service are currently permitted to act as lobbyists for only three years.

陈向东书上的解析:  段落推理为:该官员争辩说禁止政府高层官员在三年内接受院外游说集团提供的职位将阻止这些官员们在这段时间内谋生.这个推理暗自将这些官员通过院外游说之外的工作来谋生的可能性排除了,因此表述出了这种暗含的假设的选项D是正确答案.该官员的争论不依赖于假设A,B,C,或E,

因为如果一些对政府官员行为的限制是令人向往的<A>,

或如果院外游说集团成员主要不是前政府高层官员<B>,

或如果前政府低层官员也经常成为院外游说集团成员<C>,

或如果前政府高层官员可以不限制时间地为院外游说集团工作<E>,

并不能使该论述不成立.

这题我做的时候也是看着就选D了,大家肯定都会做这题,可是CD上的取非我一直都是模糊的知道意思,但是一到句子里应用就不会,我很想学会这个,为什么我想弄明白这个呢,因为我发觉难的假设题1阅读量加大 2 正确选项5个变成二选1 一个是支持,一个是假设,这时候就要用取非来排除.

我就是绕不出来的是,假设是必要条件,如果A不成立,则原文结论不成立,A就是必要条件,我想让同志们拿这题举个例子讲一下,, D为什么对我是明白的,我想知道的是为什么给A B C E 取非后原文结论还能够成立了?能给具体的一个一个的分析一下吗?

等着解答.

先谢谢再看