23. On a certain day, nine scheduled flights on Swift Airlines were canceled. Ordinarily, a cancellation is due to mechanical problems with 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 cancellation were propably due to something else.

The argument depend 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 aitlines 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 airplannes scheduled for the canceled flights are based at the same airport.

The answer isA.

解释：A采用取非法 deny it weaken the author's argument

Why?

如果把A改成only one or two aorplanes were scheduled for the nine canceled fights.

效果怎么样?削弱了吧..