第二，随着大城市的汽车和公交车数量的增加，空气污染已成为在大城市生活的另一个劣势。

Second, with the increase of cars and buses in big cities, air pollution has become another disadvantage of living in big cities.

youdao

许多城市面临着空气污染和烟雾的问题，这些大城市能够在控制空气污染，汽车和工厂产生的烟雾的问题上做些什么呢？

Many cities have problems with air pollution and smog. What can big cities do to regulate the amount of air pollution and smog generated by cars and factories?

youdao

同时在我国大城市机动车排气污染已成为城市空气污染的主要源头。

At the same time the vehicle exhaust has become the primary source of air pollution in big cities.

youdao