求助狒狒61，不管牛OR非牛都来看看

STshadow

61. Investigators concluded that human failure was not responsible for the fatal airplane crash last August, and since that time new and more stringent rules for identifying and reporting mechanical problems have been in effect. That accounts for the fact that reports of airplane mechanical problems have increased in frequency by 50 percent since last August.

Which one of the following is an assumption underlying the argument in the passage?

A.Airplane travel is still relatively safe, despite the increase in reported mechanical problems.
B.Mechanical problems in airplanes have increased dramatically since last August.
C.Mechanical problems in airplanes have not increased by 50 percent since last August.
D.Airlines are less reluctant to report mechanical problems than they previously were.
E.Mechanical problems in airplanes have become easier to detect since last August.

A.文中第一句the fatal airplane crash last August已经客观存在，说明飞机旅行并非相当安全。与文中事实相反。
B.用于识别和报告机械故障问题的更加严格的新规定已经生效，这才是the fact that reports of airplane mechanical problems have increased in frequency by 50 percent since last August的真正原因。而B选项Mechanical problems in airplanes是它因，削弱结论。
C.正确。“Mechanical problems in airplanes have increased by 50 percent since last August”是用他因来削弱结论，加上NOT，则是排除他因的假设。
D.诉诸于航空公司的主观意愿，与过去相比较，都跟现在的情况无关。
E.become easier to detect无关词。
这题BC是对立选项估摸着应该答案就在里面~但是很不了解，这BC不就是直接对事实改写否定了吗？此题很混乱，忘理解多少的就帮忙解释多少···

jasper123

Necessary assumption. Use negation.
If you negate C), you have: Mechanical problems in airplanes have
not increased by 50 percent since last August.
Then the conclusion that new and more stringent rules for
identifying and reporting mechanical problems are not the cause of
the increase of reports of mechanical problems. Thus, the
conclusion falls apart. C) is the necessary assumption.
If you negate B), the conclusion still holds.

mslancaster

想请教一下楼上的NN：


生效的新的更严格的规则查出来多出50%的机器故障  和  第一句话 那个飞

机失事不是认为原因 是什么关系？

是否全文想表达这样的逻辑拉关系：
生效的新的更严格的规则查出来多出50%的机器故障（原来就有没查出来）  

说明 那个飞机失事 很可能就是机器故障？

sophialaw81

这道题是说自从去年八月以来，一系列的措施使得查出了比原来高50%的故障。undermine，B说之后去年八月一直都上升的更多，这个倒觉得像支持，似乎反映新规起了效果。而C说的是实施新规之后的八月上升最狠，因此其上升可能有其他的原因，属于他因weaken。

Hamburger530

这道题结论在最后一句。文中提出了 since 》 percentage提高。所以c属于他因。
不可以把第一句作为 结论

因为第一句做结论 没有答案