those指代問題

ballparks

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.

(c) less of certain pollutants than gasoline or diesel fuel.

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

正確答案E中的those到底指代上文的什么東西？

新鲜的跳蚤

 haha...同一楼上的

summersmiles

those是vehicles啊，对于比较结构来说，只能用that/those代替上文中提到过的东东（不能用it），并且比较结构一定要注意是什么跟什么比，一般GMAC都会在此玩你一下，差不多看到比较结构了，再找个those、that或者一个介词什么的只要能平行比较结构两遍相比物，使之具有可比性，那么就是正确答案了。