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GWD5-Q38: Nitrogen dioxide is apollutant emitted by automobiles. Catalytic converters, devices designed toreduce nitrogen dioxide emissions, have been required in all new cars in Doniasince 1993, and as a result, nitrogen dioxide emissions have been significantlyreduced throughout most of the country. Yet although the proportion of new cars in Donia’s capital city hasalways been comparatively high, nitrogen dioxide emissions there have showedonly an insignificant decline since 1993. Which of thefollowing, if true, most helps to explain the insignificant decline in nitrogendioxide emissions in Donia’s capital city? A. More of the cars in Donia’s capital citywere made before 1993 than after 1993. B. The number of new cars sold per year inDonia has declined slightly since 1993. C. Pollutants other than nitrogen dioxide thatare emitted by automobiles have also been significantly reduced in Donia since1993. D. Many Donians who own cars made before 1993have had catalytic converters installed in their cars. E. Most car trips in Donia’s capital city aretoo short for the catalytic converter to reach its effective workingtemperature.
还是不太理解为什么E是对的：如果D城市的旅途都很短，使得装置不能有效减排，为什么1993年后就D城市就突然大幅度减排了呢？
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发表于 2013-9-11 11:32:03
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