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 gaso-

line 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

答案是E。pollutants是可数名词，应该是fewer吧。 emit应该和do对应起来吧 我怎么觉得是B。觉得白勇里面讲过，可是pdf居然不能搜索。

对于Less,记得新东方老师曾经总结过,仅供参考吧.

"GMAT中一般表示比...少时,通常使用less...than ,只有表示人的时候才用fewer"(因为简洁,且能说清楚) ,所以只在A,C,E中选,E中those是非常典型的指代,不能省,也不用they,do,does什么的,所以选E.

less of 指的是 pollutant的amount；如果用fewer就不应该加of，表示

pollutant的种类

选E.

GMAT不考名次可数还是不可数，less优于fewer;但修饰人时，用fewer