concaver凹面体concaveadj.凹的n.凹面；凹线；凹形concave-down greenbelt下凹式绿地concave perforated plate凹形多孔板concave spherical mirror凹球面镜concave mirror reflector凹面反光镜concave-inward forming内凹成形concave cylindrical lens凹柱镜片concave roll straightener双曲线辊矫直机concave slope in open pit深凹露天矿边坡concave maximum principle凹极大值原理concave-convex function凹凸函效