The ratio of the energy carried by a wave after reflection from a surface to its energy before reflection.
Велика или дубока рупа која је била узрокована бушењем.
Отвор који је направљен преко стубова који омогућавају вентилацију.
An electric current that reverses its direction at regularly recurring intervals.
A soft coal that is considered better than lignite but worst than anthracite. It's about 60-80% carbon with the rest being water, air, hydrogen, and sulfur.
Refers to the elevator that is used in a mine to transport materials and people.
The amount of heat in BTU's that is release by burning one pound of coal.
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Collection of reproductive structures found in flowering plants.
翻译
南斯拉夫
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