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

有点晕。不过我觉得似乎E是最佳答案。

those和vehicles刚好对应

我的问题是：

1。用fewer还是less？怎么判断？我认为根据后面的pollutants，要用fewer。

2。than后面的省略究竟是什么规律？谓语相同究竟补不补do？是不是必须补，还是可补可不补？E答案就没有补。在主谓相同的情况下，能不能只省略主语？比如答案B。

3。than后面的谓语如果用do，是不是必须倒装？B就没有。

正确答案是哪个啊？ 一般than后面的do要用倒装啊。

还是请steveyangxt斑竹大虾出手吧。。