feifei-23求教

georgeqian

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。我却觉得都不对。其他选项固然可以排除，但A好像也不对啊。原文中就已经明确说了“nine scheduled flights ”可见这9个航班都是scheduled，A说More than one or two airplanes were scheduled ，这不是明摆着吗？那A还有什么意义呢？不知道是不是我对这个选项本身的理解就不对？

insonbia13

hey, man, one airplane can be scheduled for several flights, right?

here it doesn't say the flights are at the same time, so one flight might be in the morning and another might be in the afternoon, using the same airplane.

wretdgdh

注意However, since it is unlikely that Swift would have the mechanical problems with more than one or two scheduled flights on a single day这个假设的存在，可以得出结论some of the nine cancellations were probably due to something else

因此结论的前提就是这一假设的成立，即More than one or two airplanes were scheduled for the nine canceled flights

gifile

I got it.

premise: mechanical problem w/ airplane --> cancel flights <=2 --> airplanes <=2

According to premise, we can conclude that number of the airplanes should be less than 2 in a single day; because two cancelled flights in a single day can not be due to 3 planes.

So, to support the conclusion: other reasons lead to the cancellation of 9, we can do this

airplanes > 2 --> cancel flights >2 --> not mechanical problem w/ airplane (other reasons)

Thus, airplanes > 2 is the basis to the conclusion, and it is the A answer.

BTW, 否定coopers 的理由。如果一架飞机飞多次航班，那么这9次cancellation就可能是因为这一架飞机的机械故障造成的，否掉了作者不是机械故障的结论，变成weaken。而且前提条件给了你信息，即cancellation<=2，最多就只有2架飞机。换句话说，一架飞机最多只能飞2次flight。所以，cooper的理由，否定了作者的前提，是错误的。