请教LSAT-5-2-4,LSAT-5-2-7

以下是引用joywzy在2003-5-20 19:33:00的发言：

7. Those who participate in local politics include people who are genuinely interested in public service and people who are selfish opportunists. Everyone who participates in local politics has an influence on the community’s values.

If the statements above are true, which one of the following must also be true?

(A) Some selfish opportunists have an influence on the community’s values.

(B) Some persons who are interested in public service do not have an influence on the community’s values.

(C) All those who have an influence on the community’s values participate in local politics.

(D) Some of those who influence the community’s values neither are interested in public service nor are selfish opportunists.

(E) All those who have an influence on the community’s values are either interested in public service or are selfish opportunists.

答案：A

以下是引用joywzy在2003-5-20 19:33:00的发言：
4. A work of architecture, if it is to be both inviting and functional for public use, must be unobtrusive, taking second place to the total environment. Modern architects, plagued by egoism, have violated this precept. They have let their strong personalities take over their work, producing buildings that are not functional for public use.

Which one of the statements below follows logically from the statements in the passage?

(A) Unobtrusive architecture is both inviting and functional.

(B) Modern architects who let their strong personalities take over their work produce buildings that are not unobtrusive.

(C) An architect with a strong personality cannot produce buildings that functional well for the public.

(D) A work of architecture that takes second place to the environment functions well for public use.

(E) A work of architecture cannot simultaneously express its architect’s personality and be functional for public use.

答案：B

这是怎么来的呢？

以下是引用joywzy在2003-5-21 16:17:00的发言：

mindfree, cranberry,谢谢你们!

其实这两题都是充分必要性.我明白这原则,可是运用起来做得一直不好.我将我的思路写下来,你们帮助看看有什么问题,好吗?

原文的思路:
who are genuinely interested in public service and people who are selfish opportunists==>Those who participate in local politics

Everyone who participates in local politiwho are genuinely interested in public service and people who are selfish opportunists==>cs===> has an influence on the community’s values

所以(我推的):who are genuinely interested in public service and people who are selfish opportunists==>has an influence on the community’s values

A:按以上思路推出

B:与以上思路相反了,错

C.逆命题,错

D.不知该怎么推,我觉得是对的,想不出反例来.

E.原文是include,不是either ,or ,错

请指正.谢谢.

以下是引用rongchao在2003-5-22 0:50:00的发言：
不用这么复杂,只要懂得集合的概念和用排除法就能马上解决.