feifei-23

renaversace

能选对答案，但是觉得道理不是很清晰，看解释版本也只有一句话

请大家帮帮忙给讲一下，谢谢先~

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.

选A

robertchu

Try "deny test".

Deny A, we get "Only one or two airplanes were scheduled for the nine canceled flights."  If so, mechanical problems with this one or two planes could very well have caused all the cancellations.  The original conclusion that the cancellations were probably due to something else is severely weakened.  So, A is a necessary assumption for the original argument to stand.

renaversace

Thanks a lot!