secondary combustion zone

例句：

1. 1. The secondary combustion zone iswhere the primary combustion takes place.
   次要燃烧区是主燃烧发生的区域。
2. 2.The researchers found that the secondary combustion zone was responsible for the pollution.
   研究人员发现，次要燃烧区是造成污染的原因。
3. 3. The city's air quality hasimproved significantly in recent years, thanks tostricter regulations on emissions in the secondarycombustion zone.
   近年来，由于对排放物在次要燃烧区的严格规定，该城市的空气质量已显著改善。