erode
/ɪˈrəud; ɪ`rod/ v[Tn esp passive 尤用於被动语态]
(of acids, rain, wind, etc) destroy or wear (sth) away gradually （指酸、 雨、 风等）侵蚀, 腐蚀（某物）
Metals are eroded by acids. 金属能被酸腐蚀.
The sea has eroded the cliff face over the years. 海水经年累月冲刷著峭壁的表面.
(fig 比喻) The rights of the individual are being steadily eroded. 个人的权利正逐渐受到侵犯.