英语语法分析

These molecules burn more cleanly than gasoline, in part because they have fewer, if any, carbon-carbon bonds, and the hydrocarbons they do emit are less likely to generate ozone.

这些分子燃烧起来比汽油更干净，部分原因是它们的碳-碳键更少（如果有的话），而且它们排放的碳氢化合物不太可能产生臭氧。

These molecules burn more cleanly than gasoline, in part because they have fewer, if and, carbon-carbon bonds, and the hydrocarbons they do emit are less likely to generate ozone.

这些分子燃烧起来比汽油更清洁，部分原因是它们的碳-碳键更少或者不存在，而且它们排放的碳氢化合物产生臭氧的可能性更小。

The game had been cleanly fought.

这场比赛打得公平。

《柯林斯英汉双解大词典》