煤烟

The inside of a chimney soon gets covered in soot.

囱里面很快就覆盖了一层煤。

Soot is usually the product of the imperfect combustion of fuel.

煤通常是燃料不完全燃物。

Soot is the product of the imperfect combustion of fuel.

煤是燃料不完全燃物。

Afterwards " fuliginous model " , " photochemical smog " after pollution, modern is being entered with " indoor air is polluted " the 3rd generation that is a mark pollutes period.

继“煤型”、“光化学雾型”污染后，现代人正进入“空气污染”为标志第三代污染时期。