短语词组短語roof -bolt t drill 頂板錨栓鑽機grouted roof -bolt 洞頂灌漿錨杆cemented roof -bolt 鋼筋混凝土錨杆roof bolt plate 錨杆墊板mine roof bolt 鑛頂螺栓expansion type roof bolt 膨脹式錨杆 返回 roof bolt