Coal mining, which liberates the stuff from coal seams, is the second-biggest source of Chinese methane after agriculture.

煤炭开采从煤层中释放出物质，是中国仅次于农业的第二大甲烷来源。

Then, to reach the buried coal seams, explosives are used to remove up to 800 feet of mountain elevation.

， 达埋藏的煤层，使用炸药移除高达 800 英尺的山体高度。

You will then walk along the low passages cut in the coal seam, and you will see men with pick-axes breaking down and cutting out great blocks of the coal.

你就可以沿着煤层中开凿的巷道走一走，会看见人们拿着镐头，把大块的煤砍下来，挖出来。