adj. 地下的,秘密的,先锋派的,隐蔽的
1、Solid low-level waste will be disposed of deep underground.
放射性水平低的固体废料将做地下深埋处理。
2、They are accused of organising and financing an underground youth movement.
他们被指控组织并资助地下青年运动。
3、The inves-tigators found that the underground pipes were badly corroded.
调查人员发现地下管道严重腐蚀。