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.

参考答案：A 采用取非法。

思路：否定More than one or two airplanes were scheduled for the nine canceled flights.将削弱作者的结论。

A：取非削弱

B：无关。

C：无关。

D：无关。

E：无关。

俺用排除法选对了，但是不是很明白为什么是这个答案。费费上的解释也不很清楚，请NN们指点～～～～

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

有多于1到2架飞机来飞这9个被取消的航班班次。也就是说，有额外的1～2架飞机来代替该飞这9个班次的飞机来飞这些航班。这样也许是可以使得原本该飞这9个班次的飞机进行其他的检查，也许是是例行的定期检查吧。只能这样解释了。

B：我觉得是削弱的。那个公司的飞机比其他航空公司机械故障少，削弱了it is unlikely that Swift would have the mechanical problems with more than one or two scheduled flights on a single day

C：无关，这longer比较莫名

D：也有削弱

E：无关