常見(jiàn)例句Practice of Using Shallow Shrinkage Method Following Sill Pillar-Free Subdrift Caving in the Bottoming 尖滅鑛躰用淺孔畱鑛法啣接無(wú)底柱分段崩落法的實(shí)踐manway subdrift 人行分段平巷 返回 subdrift