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标题: lsat 4 -- 5 [打印本页]

作者: Snazzy 时间: 2003-12-20 11:27
标题: lsat 4 -- 5
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.

Please, guys, help me analyze this one. Since good parents is a subset of good listeners. In addition to D, B should be also right?

作者: qww 时间: 2003-12-20 14:07
答案是D. A 不行因为逆命题不一定成立。B同样也不行，因为同A有一点类似的地方，文章并没有证据说明All parents who are good listeners are good parents.不成立。（只是不一定成立）。所以不能说明Bmust also be true。注意must .
当然D 肯定是对的。

作者: swimmingfrog 时间: 2004-12-2 00:30
标题: lsat 4 -- 5

all good parents share one characteristic;they are good listeners. 这句话推出good parents 是good listeners的充分条件,即如果是good parents 就一定是good listeners.那么逆否命题就应该是:如果不是good listeners,就一定不是good parents.即,parents who are not good listeners are not good parents.

B 说some parents who are good listeners are not good parents 是与逆否命题相矛盾的

作者: Bensontuo 时间: 2019-8-10 16:18

Snazzy 发表于 2003-12-20 11:27
5.    Most parents who are generous are good parents, but some self-centered par ...

5

Spot the question type: Must be true

Core of the argument:

Good parents ---> Good listeners

Generous people ( M ) ---> Good parents ---> Good listeners

* Generous people ( M ) ---> Good listeners

* Self - Center People ( S ) ---> Good listeners

Some of the " not good ' listeners are not generous

Some of the " not good " listeners are not self - center

Answers

A. Mistaken reverse

B. Could be true, could not be true

C. We only know that most of generous parents are good listeners, but we do not know if most of good listeners as parents are also generous

D. must be true

E. we can not determine that, since most is more than 51 and possible to be 100, and some is from 1 to possibly 100.

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