[求助]GWD5——38， 不明白题目和正确答案啊

GWD5-Q38:

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

这个题看了现有的讨论贴，可是都在讨论A怎么错，而我的问题在于题目中所说的矛盾就不是很看得明白，至于E作为正确答案就更不知道为什么了。还请大家帮忙再给看看，懂得的同学帮助解答一下啊！多谢了~

Nitrogen dioxide是汽车的排的污染物。Catalytic converters,可以减少汽车排放Nitrogen dioxide，从1993年开始，Donia的新车都要安装Catalytic converters，结果，most of the country的Nitrogen dioxide排放量急剧减少。尽管Donia的首都有相当大比例的新车生产，但是nitrogen dioxide 的排放量自1993年没有明显下降（insignificant decline ）。

问尽管……但是之间这个GAP怎么解释？

E：Donia的首都里行车距离太短，导致Catalytic converters起不了作用（由于行车时间短达不到 converters开始工作的温度），所以不能减少Nitrogen dioxide的排放。

你明白了就好，其实发现很多自己以为会的题还有很多疑问，如果能讲出来人家懂了才说明完全搞定这题了~~~呵呵

是的啊，lollypp真是个热心好学的人啊呵呵~再次感谢！