When the mining area enter the end stage, the optimization design of final block section and uphill pillar recovery are important.

采区进入收作阶段，最后块段与上山煤柱回收的优化设计、合理开采尤为重要。

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"I wouldn't be surprised as we move uphill that we find a section of the rock, in fact, that was modified in a shallow open-water environment, " said Ray Arvidson, rover deputy principal investigator and a geologist at Washington University in St.

CNN: Mars rovers working overtime