164.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. 一般这个ving是现在分词还是动名词？ 还是应该按照什么原则判断？ 谢谢 注：这种题目，我比较困惑，因为xdf不是常说v > adj >n >ving（现在分词）！ 但是我每次老师在n>.
Ving Rhames
