myice

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
答案：D， 这种some, most, all题怎么做？有什么思路吗？
A: 1. 这类题目首先要把题目读清楚, 并将思路局限在题目中所给的关系内.  
Must be true的题目一般可以正推出来, 因为如果一定对的话, 原文必须给出一个真命题, 还有一个方法就是举反例, 原文没有限制的都可能. 比如说最后一句:all good parents share one characteristic; they are good listeners. 这句话中的关系就是:只要是good parents--->good listeners. 其逆否为等价命题,可以得到:not good listeners-->not good parents.
这里可能正确也可能错的是:good listeners都是good parents;不是good parents-->not good listeners.  此二命题分别是逆命题和否命题, 即可能对也可能错. 因为原文没有对此二命题有限制, 两种情况都可能. 我建议在读题时不要考虑这些引申命题, 在读选项时要考虑.
A. 错, 逆命题, 可错, 如逆命题错, 不成立
B. 错, 逆命题, 可对, 如逆命题对, 不成立
C. 错, most错, 原文没有给出两者关系
E. 错, 原文没有给出两者关系
Some表示有一些, 可以是一个. most表示多数, 要大于50%. 读题是要注意原文所给的范围. 可以画图联系. 这类题我一般用排除和正推直接做.