◆记忆方法二： 联想方式：und有难度；e r人 ;grou狗肉；nd 拿到 记忆方法：生活有难度的人是在社会的下层了;狗肉拿到地上去放;under+ground，下层地面上的（铁路系统）-地铁 ◆记忆方法三： 词根词缀记忆法：underground地下的（under+ground地）,“under-”表示“在…下” ◆记忆方法四： underground (考频：2) n.［the ～］地铁［=(美)the subway］ a.①地(面)下的：an underground passage一条地下通道 ②秘密的：underground activities地下活动 ad.①在地下：Miners work underground.矿工在地下工作。 ②秘密地：The news has been passed on underground, but not in the official newspapers.这一消息已秘密传开，但尚未正式见报。
The office building has an underground parking. 这栋办公楼有地下停车场。
N-COUNT. 地铁;地下铁路. The metro is the underground railway system in some cities, for example in Paris.
Perhaps you have seen colorful limestone cave and underground river, but the eighteen caves here are Mesozoic lava land forms, which is produced by the movement, cracking and weathering of the earth's
