underground dam地下坝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 levelling坑道水准测量underground formation地下岩层underground coal fire煤矿火灾underground operation井下工作underground vibration地铁振动underground storeroom地下仓库underground detection地下探测underground transport井下运输underground structure地下结构,地下构筑物underground cable box地下电缆接线盒