The most important sources请帮忙翻译下The most important sources of air_英语解答

The most important sources请帮忙翻译下
The most important sources of air pollution in China are the emissions of().
1.plane 2.motorcycles.3.Auto 4.industrial emissions

人气：386 ℃　时间：2020-02-02 09:02:23

解答

中国最重要的空气污染来源是什么的排放
1、飞机2、摩托车3、汽车4、工业排放
3或4?