Increasing in mining cost, industry-wide earningratio should be more than that of national debt in the corresponding period.
矿山开采成本随矿山开发的深入，是逐年上升的，其行业收益率应大于同期国债收益率。
2
When company's assets earningratio is higher than the debt capital cost proper to increase in debt to raise its business performance;
当公司资产收益率高于债务资本成本时适当增加负债可以提高其经营业绩；
3
We need to know asset portfolio earningratio distribution function uniting , but the distribution function uniting so are sometimes unable now casually express out.