求教FEIFEI-23

jiangmiss

 

求教FEIFEI-23

23. On a certain day, nine scheduled flights on Swift Airlines were canceled. Ordinarily, a cancellation is due to mechanical problems with the airplane scheduled for a certain flight. However, since it is unlikely that Swift would have the mechanical problems with more than one or two scheduled flights on a single day, some of the nine cancellations were probably due to something else.

The argument depends on which one of the following assumptions?

(A) More than one or two airplanes were scheduled for the nine canceled flights.

(B) Swift Airlines has fewer mechanical problems than do other airlines of the same size.

(C) Each of the canceled flights would have been longer than the average flight on Swift Airlines.

(D) Swift Airlines had never before canceled more than one or two scheduled flights on a single day.

(E) All of the airplanes scheduled for the canceled flights are based at the same airport.

正确答案是A, 但题目说it is unlikely that Swift would have the mechanical problems with more than one or two scheduled flights on a single day, 所以我觉的假设应该是SWIFT至少有5辆飞机, 才能满足. 但A说More than one or two airplanes were scheduled for the nine canceled flights, 所以不解, 请赐教.

 

Fabulous

我来说说我的理解。我也对这道题琢磨了很久，觉得很怪，跟以前做的假设题有点不同。
文章的第一句话是说9个航班被取消了，（第二句省略），然后however后面说的是因为不太可能多于2次的航班在同一天出现机械问题，所以有些取消的航班是因为别的原因而不是因为机械问题。
这个推理本身是没有问题的。问题出在however后面的那个原因，这个原因是有问题的，机械问题不应该跟航班有关系，而是应该跟飞这趟航班的飞机有关系。原因需要一个能够成立的必要条件，这个必要条件就是：有多与两架的飞机被安排飞这9趟航班。一个极端的例子，如果这9趟航班是一架飞机飞，如果它出现机械问题，所以9趟航班都因为这个机械问题这个而被取消，这个原因就不成立。再来一个例子，如果是三架飞机飞这9趟航班，平均一架飞机飞3趟，如果一架飞机出现机械问题，导致3趟航班取消，这个原因还是不能成立。所以这个给出的假设是原因成立的必要条件而不是充分条件。充分条件是：至少需要至少8架飞机，而且每次只允许一架飞机出现机械问题。我也快晕了

这题的难点在两个地方：
1，assumption不是在加强结论，而是在说前提条件的有效性。如果however后面给出的前提没有意义，结论也不可能成立。
2，混淆概念：本意是想说飞机出现机械问题，而变成了航班出现机械问题。飞机和航班这里需要搭桥。

我也需要人帮忙理解这道题。

heilongh

本题的结论是：since it is unlikely that Swift would have the mechanical problems with more than one or two scheduled flights on a single day, some of the nine cancellations were probably due to something else.

结论：由于不可能在一天之内取消一个以上的航班，因此应该由其他原因。

前提取非如果能削弱的话就是正确答案。A中 More than one or two airplanes were scheduled for the nine canceled flights. 取非得：只有一家飞机在跑这9个被取消的航班。那么也就是说，只要一架飞机坏了，这9个航班在一天内被同时取消是可能的。也就是说，削弱了题目中“一天之内取消一个以上航班不可能”的结论。