adj.平凹的
plano concave 平面平一面凹的(平凹的)
His figure looks very funny in the concave mirror. 他的样子在凹镜里显得非常可笑。
An indented or concave surface or area. 凹陷，洼地凹的表面或地区
Just as a double convex lens enlarges, so a double concave lens reduces. 正象双凸透镜可以放大那样，双凹透镜也可以缩小。
A concave molding with a cross section that approximates a quarter circle. 飞檐的凹圆线脚截面近于九十度弧的凹线脚
