Nitrogen dioxide is a pollutant emitted by automobiles.  Catalytic converters, devices designed to reduce nitrogen dioxide emissions, have been required in all new cars in Donia since 1993, and as a result, nitrogen dioxide emissions have been significantly reduced throughout most of the country.  Yet although the proportion of new cars in Donia’s capital city has always been comparatively high, nitrogen dioxide emissions there have showed only an insignificant decline since 1993.

Which of the following, if true, most helps to explain the insignificant decline in nitrogen dioxide emissions in Donia’s capital city?

A  More of the cars in Donia’s capital city were made before 1993 than after 1993.

B  The number of new cars sold per year in Donia has declined slightly since 1993.

C  Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Donia since 1993.

D  Many Donians who own cars made before 1993 have had catalytic converters installed in their cars.

E  Most car trips in Donia’s capital city are too short for the catalytic converter to reach its effective working temperature.

参考答案是E，翻看了以前讨论的帖子，NN们多偏向E这个答案。

但是，我还是想坚持A。

E。从逻辑上没错，但是并没有回答原文里new car 增加这个前提。它不是就是论事的精神，是GMAT里面的无关的选项。

污染减少不明显是跟新车有关，跟旧车没有关系，旧车摆在那里数量不变，该影响污染的还是会污染，也就是说新车的DEVICE如果没有效果的话，污染减少就不明显

如果考虑到逻辑关系的话，A里为什么没有设计到DEVICE，题干中说了一大段关于DEVICE的起不是浪费了篇幅

 A不能解释为什么减少

除非说老车排的量有增加的趋势，且大于新车减少的排放量

如果老车的排放量是一定的，无论老车有多少，排放量在新车上的减少应该是体现的出来的

所以A不能完全说明原因。

E比较合适，原来预计要减少的排量因为没有发挥作用没有实现，这样结果是唯一的。

谢谢两位的回复，但是我还是觉得想不明白：

A这个答案里面是涵盖了device这个概念的，因为实际投入使用的新车大部分都是1993年前生产的，而这些新车没有安装device，所以造成看起来首都的新车比例虽然增加(因为增加的新车大部分是1993年前生产的，没安装devic），但是污染的减少并没有明显的减少。

我感觉：你们反复提到的“老车”的概念是不是说1993年前生产的那些车呀？我觉得不是这样的，这里A提到的是大部分新车都是1993年前生产的。所以，这些车大量的投入了使用。造成污染减少不明显。我怎么都觉得这个就事ETS答案的风格。

我记得最经典的那个题目：冬天刮风树枝砸车子的题目，那个就是和这个题目的思想很接近，ETS说什么就什么，无关的东西就算有道理也不是答案呀。所以，E不是答案。

做OG逻辑的时候我基本第一遍到了后面的题目都不错的，自觉地逻辑对自己来说太简单了，但是现在到了GWD，发现好像很多答案的风格和OG都不一样了。好些题目我都觉得GWD给出的答案不对，不是ETS要的那种答案。这个题目就是我百思不得其解的之一。我正在想：是不是自己建立起来的ETS的逻辑思想出了问题。正在困惑中。

A. More of the cars in Donia’s capital city were made before 1993 than after 1993.

The answer A can be right if "More of " is changed to "Almost". Think of this: 51% cars before 1993 without the device vs. 49% cars after 1993 with the device. What if the 49% cars after 1993 with the device, which are FEWER part, make more significant declines?

E. Most car trips in Donia’s capital city are too short for the catalytic converter to reach its effective working temperature.

There is a drawback, the statement of "reach its effective working temperature", in its question stem . Such a statement doesn't show a directly logical relation of decline and emssions, which must be infered based on common senses beyond the basic knowledge of this question. However, it is the BEST one we have to choose.