нүүрс нунтаглах тээрмийн аэродинамик
Нунтаг нунтаглах нүүрсний. Introduction to Coal Coal is a kind of carbonized fossil mineral. It is organized by carbon, hydrogen, oxygen, nitrogen and other elements, majority used as fuel by human. At present, the coal has 63 times of explored reserve volume than petroleum. Coal was called the black gold and the food of ...