feifei23还是不太明白

看到网上有求助的但还是不太明白,请高人再指点,谢谢(另,问题这里没有好像是weaken)

谢谢

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.

先读题：
Fact：一天取消了9个航班
回忆的事实，也算Fact吧：以前没有发生过超过2个航班因为机械故障而取消的情况
文中已经阐述的逻辑关系，给定的推断：通常航班取消是由于飞这个航班的飞机故障导致的。
文中导出的结论是：一天取消9个航班不是机械故障造成的。
要求找出隐含的假设条件，哪个最合适。

A：9个航班不是由一两架飞机来飞的
B：这家航空公司机械故障比较少
C：取消的都是较长的航线
D：以前从未一天取消过2个以上的航班
E：所有被取消的航班，飞机都停靠在同一个机场

注意逻辑题不允许你自行推测。在这个题目中，文中没有说具体的原因，你自己推测的原因不算数，例如E你可以推测是机场造成了问题，或者C你可以推测是燃油供应的问题，但是无法对应题目的要求：说明“不是机械故障”的“隐含的假设”。只有A，将这个假设加入到与原文中，整个原文意思变成：“如果是机械故障导致的，那么这9个航班所需要的众多飞机要同时出现故障；根据以往的情况机械故障最多同时影响一两个航班也就是说从没发生过这么多飞机同一天故障的情形，显然不太可能是机械故障导致的”。最清楚和顺畅。
而B和D只不过是文中已经提到的Fact再重复也不能增加信息，更不是“隐含”的假设，所以应该能够一开始就排除掉。