combustion phases

例句：

1. 1.The combustion phase of the chemical reaction is critical to understanding its efficiency.
   化学反应的燃烧阶段是理解其效率的关键。
2. 2.During the combustion phase, the flame can be seen flickering and expanding.
   在燃烧阶段，火焰可以看见闪烁和扩张。
3. 3.The combustion phase is a crucial part of the process that leads to the formation of carbon dioxide.
   燃烧阶段是导致二氧化碳形成的工艺中至关重要的部分。