请教主LSAT-1-1-13,14

以下是引用joywzy在2003-5-4 16:14:00的发言：
13. Top college graduates are having more difficulty demonstrating their superiority to prospective employers than did the top students of twenty years ago when an honors degree was distinction enough. Today’s employers are less impressed with the honors degree. Twenty years ago no more than 10 percent of a given class graduated with honors. Today, however, because of grade inflation, the honors degree goes to more than 50 percent of a graduating class, Therefore, to restore confidence in the degrees they award, colleges must take steps to control grade inflation.

Which one of the following is an assumption that, if true, would support the conclusion in the passage?

(A) Today’s students are not higher achievers than the students of twenty years ago.

(B) Awarding too many honors degrees causes colleges to inflate grades.

(C) Today’s employers rely on honors ranking in making their hiring decisions.

(D) It is not easy for students with low grades to obtain jobs.

(E) Colleges must make employers aware of the criteria used to determine who receives an honors degree.

答案：A，我觉得B，C也行啊？有什么区别是？A是怎么假设的呢？

以下是引用joywzy在2003-5-4 16:14:00的发言：

14. Either Perry’s faction or Tucker’s faction, but not both, will win control of the government. If Perry’s faction wins, the nation will suffer economically. If Tucker’s faction wins, the nation will suffer militarily.

Given the statements in the passage, which one of the following statements must be true?

(A) It is possible, but not certain, that the nation will neither suffer economically nor suffer militarily.

(B) If the nation suffers economically, it is certain that Perry’s faction has won control of the government.

(C) It is certain that the nation will suffer either economically or militarily, and also certain that it will not suffer both.

(D) If the nation suffers militarily, it is possible, but not certain, that Tucker’s faction has won control of the government.

(E) If the nation suffers both economically and militarily, it is certain that neither Perry’s faction nor Tucker’s has won control of the government.

答案：D，一点也不知该怎么做这种题？

不好意思，问题多多，谢谢了。

以下是引用mindfree在2003-5-5 4:42:00的发言：
2. 同意Jacy的看法, 一个真命题的逆命题或否命题不一定成立, 既可能成立,也可能不成立. A发生则B发生, 现在B发生了, A可能是原因,也可能不是.

以下是引用mindfree在2003-5-5 4:42:00的发言：
1. 你最好把你的思路写出来,我们看看是错在哪里.

以下是引用mindfree在2003-5-5 22:35:00的发言：
原命题为：Ａ－－＞Ｂ
逆命题为：Ｂ－－＞Ａ
否命题为：非Ａ－－＞非Ｂ
逆否命题为：非Ｂ－－＞非Ａ

原命题和逆否命题为等价命题．如果原命题成立，逆否命题成立．vice versa.
逆命题和否命题为等价命题，如果逆命题成立，否命题成立．vice versa.