cave / keɪv; kev/ n
hollow place in the side of a cliff or hill, or underground 洞穴.
> cave v
[I] (usu 通常作 go caving) explore caves as a sport 洞穴探险运动: He likes caving. 他喜欢洞穴探险运动.
(phr v) cave in fall inwards; collapse 塌陷; 坍方; 坍塌: The roof of the tunnel caved in (on the workmen). 隧道顶坍塌（压住工人）. * (fig 比喻) All opposition to the scheme has caved in. 所有反对这一计划的意见都否定了.
# `cave-dweller n = caveman.
`cave-in n sudden collapse of a roof, etc （屋顶等）突然坍塌.
caveman / ˈkeɪvmn; ˋkevˏmæn/ n (pl -men / ˈkeɪvmen; ˋkevˏmɛn/)
1 person living in caves, esp in prehistoric times 穴居人（尤指史前时代的）.
2 (infml 口) man of crude or violent feelings and behaviour 野蛮人; 粗野的人.