同根常考词汇：需掌握
◆underground[’ndɡraund]n.地下，地铁：a.地下的；地下组织的：ad.在地下
举例：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。同形：ground[ɡraund]n.土地，战场，场地
◆underline[，nd‘lain]v.在……下面划线；强调
举例：That article underlined the same problem.
那篇文章强调了同一个问题。
◆undermine[，nd’main]v.渐渐破坏，逐渐削弱
举例：Badgers had undermined the foundations of the church.
獾在这座教堂的地基处打了洞。
同形：underneath[，nd‘niθ]ad.在下面：prep.在……下面：n.下部，底部
◆underwear[’ndw]n.内衣
举例：He had removed his underwear.
他已脱去了内衣。