关于一道PREP08逻辑的迷惑选项！求讨论！

六月的水蜜桃

104.

Nitrogendioxide is a pollutant emitted by automobiles. Catalytic converters, devices designed to reduce nitrogen dioxideemissions, have been required in all new cars in Donia since 1993, and as aresult, nitrogen dioxide emissions have been significantly reduced throughoutmost of the country.  Yet although theproportion of new cars in Donia's capital city has always been comparativelyhigh, nitrogen dioxide emissions there have showed only an insignificantdecline since 1993.

Whichof the following, if true, most helps to explain the insignificant decline innitrogen 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 havealso been significantly reduced in Donia since 1993.

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

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

答案是E
我理解E是对的，但是D不是也可以解释吗？如果之前的车子都已经装过Converter了，那么新的车就算也都要装，从比例来说也不会有大幅的下降啊。。。
如果有人说D没有提及其他城市的情况，E不也没有提到吗？

mayarie

我想的是，D说的是many Donians，题里已经说了整个country nitrogen排放下降了，要解释的应该是capital city为什么和country不同？

mkiciy

mayarie 发表于 2014-6-16 16:28
我想的是，D说的是many Donians，题里已经说了整个country nitrogen排放下降了，要解释的应该是capital cit ...

同意楼上