first caving of the immediate roof是什么意思


中文翻译直接顶初次垮落

网络释义

1)first caving of the immediate roof,直接顶初次垮落2)the pace of direct top collapsing initially,直接顶初次垮落步距3)initial caving,初次垮落4)the pace of top coal collapsing initially,顶煤初次垮落步距5)roof caving,初次落顶6)roof caving,顶板垮落

用法例句

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