The evergreen forests of the Amazon and Congo basins, for example, are generally fire-free because the closed canopy maintains a level of humidity that inhibits burning.
例如，亚马逊和刚果盆地的乔木通常是防火的，因为它们遮天的树冠保持了一定的湿度，抑制了燃烧。
2
Free radicals are produced mainly by the body burning oxygen, partly as a result of smoking, pollution and sunlight.
游离基主要是在身体消耗氧气时产生，部分是因吸烟、污染和日照所致。
3
Determining the iron content in organism by oxygen bomb burning incineration is easy to operate, fast to finish, free of pollution and reliable in different conditions.