secondary gas

例句：

1. 1. The chemical reactionis a complex process involving many different typesof gases.
   化学反应是一个复杂的过程，涉及许多不同类型的气体。
2. 2. The firefightersused a hose to extinguishthe secondary gases.
   消防员使用软管来扑灭二次气体。
3. 3. Thescientist conducted experiments to studythe properties of secondary gases.
   科学家进行了实验，研究次级气体的性质。