基本解释中间平巷同根派生 subdrift相关词英汉例句Practice of Using Shallow Shrinkage Method Following Sill Pillar-Free Subdrift Caving in the Bottoming 尖灭矿体用浅孔留矿法衔接无底柱分段崩落法的实践manway subdrift 人行分段平巷subdrift更多例句