由于凹面与凸面之间没有磨损，螺母可以重复使用。

Because there is no abrasion between the concave and convex, the nut is reusable.

红血球的双凹面圆盘形可以增加它的表面积，以利气体的扩散。

Red blood cell with a biconcave disc shape is to provide a large surface area to volume ratio to facilitate the diffusion of gases.

介绍了一种通过微细加工技术即二次X射线曝光制作凹面光栅的方法。

The technique of fabricating concave gratings in PMMA by double X-ray exposures is described.

犯罪预防尤如一面模具，它的凸面是社会安全保障，它的凹面是个人自由保护。

It is like a mould, which convex is the guratee of the security to society, and whose concave is the protection of th…

各个线条及面对观察者显示多个反光面，凹面或凸面用于令人激动的形状，应该象个自然物体。

Various lines and shapes show planes of light reflections to the viewer. Convex and concave areas make for exciting shapes. Realistic design should look like a natural object.