用作定语
▲～+n.
 There is an underground car park.这里有一个地下停车场。
The spy never told his family about his underground activities.那个间谍从来不把他的地下活动告诉他的家人。

1.underground还可用作副词,表示“在地下”“秘密地”。例如:
The railroad track goes underground for a short distance.铁轨有一段不长的路程铺设在地下。
The news has been passed on underground.这消息被秘密传开来。
2.underground还可用作名词,表示“地铁”“地下组织〔活动〕”。例如:
London has a well-developed underground system.伦敦的地铁很发达。
He is a member of the underground.他是一名地下组织的成员。

［同义词］   buried, secret