sharp dropping coal seam的意思|示意
美 / /
英 / /
尖降煤层
sharp dropping coal seam的网络常见释义
倾斜煤层 ...倾斜煤层；超前剥离 [gap=1063] coal mine；double pits dynamic regulating mode；double pit-leaping mining method；sharp dropping coal seam；advance stripping ..