Using the principle of "ore deposit is controlled by structure" and through combining of trench with hole, the new geological reserves of ore are detected that prolongs the service life of mine.

前言：利用构造控矿原理，采用坑钻相结合的方式，探明新增地质储量，延长矿山服务年限。

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Part of his strength - and mine - came from you, the American people, to whom he dedicated his life of public service.

他的这种力量部分来自你们美国人民，为了你们，他愿意将全部生命奉献给公共事业。

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The optimal service life of a mine is discussed theoretically from economic point of view by analysing the cost and benefit.

本文采用成本与效益分析的方法，从经济上对矿井合理服务年限的定量问题，作了理论上的探讨。

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