Gas is a similar issue. Gas is also a biological product. And as you think of gas, well, you're familiar with gas. And here's a different way of mining coal.
天然气也是类似的。天然气也是一种 生物产品。当你想到天然气时， 你会觉得很熟悉。开采天然气的方法 是不同于采煤的。