Underground car井下汽车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 shield tunnel地铁盾构隧道underground-water table地下水位underground stratification地下成层现象underground material depot地下物资库Underground Water Dynamics地下水动力学underground space planning地下空间规划underground energy storing地下储能underground traffic system地下交通系统underground railway survey地下铁道测量underground storage of gas地下储气