lsat-3-4-7

ymxl4611

5.     Most parents who are generous are good parents, but some self-centered parents are also good parents. Yet all good parents share one characteristic: they are good listeners.

If all of the statements in the passage are true, which one of the following must also be true?

(A) All parents who are good listeners are good parents.

(B) Some parents who are good listeners are not good parent.

(C) Most parents who are good listeners are generous.

(D) Some parents who are good listeners are self-centered.

(E) Fewer self-centered parents than generous parents are good listeners.

the anwser is (D), why (B) is not correct?

Thanks and Merry Christmas!

dalunzi

B只能说是“may be true”，题目是问must also be true。

题目说了Yet all good parents share one characteristic: they are good listeners.我们都知道逻辑中反过来则“不一定”正确（注意不是“一定不正确”），即all good listeners 不一定是good parents 。而B是顺应“一定不正确”的逻辑得出的，所以不对。（不好意思，用了很多颜色，权当庆祝圣诞节了）

ymxl4611

果然很有喜庆的色彩,谢谢楼上!

祝楼上节日快乐!

Bensontuo

ymxl4611 发表于 2004-12-23 22:20
5.     Most parents who are generous are good parents, but some self-centered pa ...

Spot the question type: Must be true

Core of the argument:

GP ( Most ) ---> GDP --- GL

SCP ( Some ) ---> GDP ---GL

GDP ---> GL

So

1. GP ( Most ) ---> GL  

2. SCP ( Some ) ---> GL

A. Mistaken reverse

B. It is could be true answer, but we dont know if it must be true. ( Since Most could be 100/100 )

C. Mistaken Reverse

D. If at least 1 SCP ---> GL, then it must be true that at least 1 GL ---> SCP

E. We can't inferred that.