送交者: fair 于 2006-2-03, 12:23:53:

回答: 考虑进去的话，按何老的算法，中国都比美国安全了！ 由 skywalker00 于 2006-2-03, 12:09:07:

surface mine has much high productivity, ie, one of the company with 500 employees has annul production of 40million tons of coal.

加跟贴