Questions 80-81 are based on the following.
The program to control the entry of illegal drugs into the country was a failure in 1987. If the program had been successful, the wholesale price of most illegal drugs would not have dropped substantially in 1987.
80.
The argument in the passage depends on which of the following assumptions?
(A) The supply of illegal drugs dropped substantially in 1987.
(B) The price paid for most illegal drugs by the average consumer did not drop substantially in 1987.
(C) Domestic production of illegal drugs increased at a higher rate than did the entry of such drugs into the country.
(D) The wholesale price of a few illegal drugs increased substantially in 1987.
(E) A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in their wholesale price.
80.
The only choice that must be true in order to conclude legitimately from the drop in the wholesale price of illegal drugs that the program was a failure is choice E, the best answer. If the drop in price was caused by a drop in demand, there is no reason to suspect that there has been any increase in supply caused by drugs entering the country.
The other choices can be false without affecting the argument. The supply of illegal drugs need not have dropped (choice A), and the retail price could have dropped (choice B). The entry of illegal drugs could have risen at a higher rate than domestic production (choice C), and no illegal drug need have undergone a substantial price rise (choice D).
这些天在看zeros提供的《逻辑基础知识》，这是我用充分条件假言判断的概念和判断方法解80题的思路，请大家指正！感谢！另外，还有哪些朋友也看了《逻辑基础知识》不妨跟个贴，以后就可以多交流啦！
充分条件假言判断是断定充分条件关系的假言判断。事物情况p 是事物情况q 是充分条件是指：有p 一定有q ，但无p 未必无q (因而无q 一定无p ，有q 未必有p )。
例如“天下雨”就是“地上湿”的充分条件。充分条件假言判断的标准形式是“如果p ，那么q ”(日常语言中也表述为“只要p ，就q ”，“一旦p ，则q ”等)，其中，p 称为前件，q 称为后件。
一个充分条件假言判断，只有在前件真且后件假的情况下才是假的，这种真假关系可用下表刻画：
p
q
如果p ，那么q
真
真
真
真
假
假
假
真
真
假
假
真
运用以上逻辑学概念解此题：充分条件判断题
如果the program 失败了（p），那么批发价下降（q）（如果the program没有失败，那么批发价不会下降）
根据上述，可见我们只需找出p真q真 /p假q真/ p假q假 中的任何一种情况就可以找出题目假设了，从而使这个判断成立，只有E满足了p假q真/ p假q假这两种情况（因为题目说A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in their wholesale price.也就表明了p这个充分条件有可能为“真”---除了a drop in demand 这个原因以外，另外的原因就是题目说的program fail，或者为“假”---另外的原因有可能是其他的而不是program fail）所以（E）提供了假设，使这个判断成立。
问一下LZ，哪里能搞到这个《逻辑基础知识》啊？谢谢！
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