求翻译：圆曲面是由许多弯曲转折的相对平面延续而成，每一相对平面上，都具有它一定的明度变化，所以圆面的明暗层次比平面多。从浅到深逐步地过渡，变化比平面的复杂。圆球体的明暗调子分布，是呈圆周形的扩展，明暗变化从圆球上一小块与光源垂直的的亮调子，开始向四周扩散逐渐过渡为灰调子，再继续过渡到明暗交界线并由此转为暗调子，它的亮、灰、暗三大关系的变化，就不象立方体那样单纯明确。是什么意思？

Round surface is composed of many curved continuation of transition from the relative flat, each relative to the plane, it must have the brightness changes, so the round face of the plane more than shades. Gradually from shallow to deep transition, changes in the complex than the plane. Spherical di

正在翻译，请等待...

The round curved surface is becomes by many curving transition relative plane extensions, in each relative plane, all has its certain brilliance change, therefore the disc light and shade level are more than the plane.From to deep gradually transits shallowly, changes compared to plane complex.The s

Circular surface is composed of many bends-bend in the relatively flat and continued but, on each plane, has a certain lightness change, so a round face and dark more levels than plane. In the gradual transition from shallow to deep, change than the complex plane. Sphere of dark tone distribution, i