underground air矿内空气
undergroundadj.地下的;秘密的adv.在地下;秘密地n.地下;地铁;地道;秘密活动
underground water of mining pit矿坑地下水
underground traverse adjustment地下导线线测量
underground blast hole drilling井下炮眼钻凿
underground water power station地下电站
underground locomotive for mine矿用井下电机车
underground maintenance vehicle井下维修车
underground fracture connection井底裂缝连通
underground engineering station地铁工程