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.
结论问的是解释 insignificant decline since 1993作者: Analee 时间: 2010-9-14 00:24
UP主看错结论了吧
我分在assumption里了 个人看法啊作者: wudiyeah 时间: 2010-9-14 00:42
这题今晚上刚做，我第一次就得答案了呀。。。 help explain就是现象解释题嘛。。给出两件看似矛盾的事，要你能给出个合理的解释，使两个看似矛盾的结果同时成立。作者: frankzhiwei 时间: 2010-9-14 12:05
哦，貌似我看反了呀~作者: starchang14 时间: 2010-9-14 12:37
我觉得题里说 "Yet although the proportion of new cars in Donia's capital city has always been comparatively high"就是叫我们不要去考虑是不是因为new car而产生的原因,这样就可以把注意力转移到catalytic converter上.