[求助]大全-18-9 前面没人问过的B

9. Technically a given category of insurance policy is underpriced if, over time, claims against it plus expenses associated with it exceed total income from premiums. But premium income can be invested and will then yield returns of its own. Therefore, an underpriced policy does not represent a net loss in every case.

The argument above is based on which of the following assumptions?

(A) No insurance policies are deliberately underpriced in order to attract customers to the insurance company offering such policies.

(B) A policy that represents a net loss to the insurance company is not an underpriced policy in every case.

(C) There are policies for which the level of claims per year can be predicted with great accuracy before premiums are set.

(D) The income earned by investing premium income is the most important determinant of an insurance company’s profits.（E）

(E) The claims against at least some underpriced policies do not require paying out all of the premium income from those policies as soon as it is earned.

答案是E，明白。但不明白为什么B不是？

原文的结论是：Therefore, an underpriced policy does not represent a net loss in every case. 即(充分必要条件）：underpriced policy --> 不是net loss in every case.

而B（充分必要为）：net loss --> 不是underpriced policy  in every case. 不刚好是原命题的逆否命题吗？请高人指教！

偶太笨了，不要笑哦！

还是没有人理呀,,, 估计问题太菜，NN都不屑一顾。

唉，在睡觉前顶上一把。期待好人.....

1。原文结论并没有充分必要关系

2。问题问的是假设，不是问下列哪个选项能从原文推出。所以即使B是逆否命题，也不是假设。

谢谢LAWYER的解释（总是这么精当）！

能不能再请LAWYER解释一下为什么这个结论不是充分必要关系呢？我记得在你的充分必要指示词的贴子上有一个例句：

No citizen can be denied the right to vote. denied the right to vote(充分条件)—>no citizen(必要条件)  

我作这道题的时候就是这么想的，不知道错在哪？有什么辩别标志么？

另外你指出即使是逆否命题，也不是假设。请问这是针对这道题而言，还是其它题也如此？因为有些因果型的假设（非因非果）正好是逆否命题，所以有些困惑。

问题太菜，不过还是希望LAWYER GG多抛砖哦！多谢啦！

题目：an underpriced policy does not represent a net loss in every case. --> 有些 underpriced policies 不是 net loss.但是并没有说net loss是不是都是 underpriced policies.

不知道E应该怎么翻译呢？The claims against at least some underpriced policies do not require paying out all of the premium income from those policies as soon as it is earned.

如果这题该为which of the following can strenthen the conlusion?B是不是可以呢？

谢谢lawyer 和tuzq! 晚上睡觉前又想了想，觉得自己有点专牛角尖了。其实这道题不难：

前提一：如果“成本大于收入”，就是underpriced policy

前提二：（保险金）收入可以有其它收益（换言之，“成本”不一定大于“收入+其它收益”，如果是这样就是net loss了）

结论：underpriced policy（即“成本大于收入”）并不是在每个情况下都是net loss（即“成本”大于“收入+其它收益”）

而E的意思是说：在有些情况下，underpriced policy（即“成本大于收入”）不会立即将所有的保险金收入用于支付索赔。（因为如果这样的话，保险金的收入将无法进行投资而带来任何收益，也就会造成“成本”大于“收入+其它收益”）,正好是假设。

以前看过Lawyer 关于充分必要指示词时有个None的结构（No citizen can be denied the right to vote.），瞅着那道题的结构跟这道题挺象，就想着把它搬到这题，结果弄巧成拙。是不是我把一些本是out of scope的词看做是充分必要关系了呢？以后做这种题时如何才能避免这样的错误呢？再请指教！

我觉得B是错误的：因为如果一个policy是net loss即“成本”大于“收入+其它收益”的话，那么它必定是一个underpriced policy（因为“成本大于收入”），违背了原文的逻辑关系。所以我觉得不论是假设还是加强都是错的。

这么理解B选项，看看是不是会更好：把代表net loss policy和underpriced policy想成两个嵌套的同心圆，里面的是net loss policy，外面的是underpriced policy，它们是一个包含与被包含的关系。里面的圆肯定属于外面的圆，但是外面的圆不一定是里面的圆。

明白了。

绕了我好几天了。