大全016

16        Because natural gas is composed mostly of methane, a simple hydrocarbon, vehicles powered by natural gas emit less of certain pollutants than the burning of gasoline or diesel fuel.

(A) less of certain pollutants than the burning of gasoline or diesel fuel

(B) fewer of certain pollutants than burning gasoline or diesel fuel do

(C) less of certain pollutants than gasoline or diesel fuel

(D) fewer of certain pollutants than does burning gasoline or diesel fuel

(E) less of certain pollutants than those burning gasoline or diesel fuel

答案：E。这个从vehicles和those的并列关系上没有什么问题，但是这个比较结构than前面是vehicles powered by...emit less...than those...为什么than前面有动词emit而than后面指只给出了名词结构但是没有do呢？不是说比较从句谓语与主句谓语相同，可用do，did或does代替吗？这里怎么干脆就省略了呢？请大牛牛多多指教哦：）

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