2 sentences

1. 汽车尾气在城镇里造成了严重的污染。

   qì​chē wěi​qì zài chéng​zhèn lǐ zào​chéng le yán​zhòng de wū​rǎn.

   Car exhaust causes serious pollution in towns.

   Source: Tatoeba

2. 汽车尾气排放是城市空气污染的主要来源之一。

   qì​chē wěi​qì pái​fàng shì chéng​shì kōng​qì wū​rǎn de zhǔ​yào lái​yuán zhī​yī.

   Vehicle exhaust is one of the main sources of urban air pollution.

   Source: Dong Chinese Dictionary