求翻译：立方体是平面的组合，体面转折明确，面与面的分界线非常清楚，平面上的明暗变化比较单纯，易于观察理解。光源从立方体的左侧上方照射，向上的面接近垂直受光而成亮面，左边的面因倾斜受光而成灰面，右边的面因背光而成暗面。它的亮、灰、暗三大面的明暗调子是突变的，因此区分很清楚。是什么意思？

Cube is a combination of flat, decent turning clear dividing line between the surface and the surface is very clear, light and shade on the plane change is simpler, easier to understand observed. Light irradiated from the top left side of the cube, the face up close to the vertical surface by bright

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The cube is the plane combination, the dignified transition is clear about, the surface and the surface separatrix is extremely clear, in the plane light and shade change quite is pure, easy to observe the understanding.The photosource place above shines from cube left side, but but the upward surfa

Cube is a combination of the plane, a decent turn clear, very clear dividing line between surface and surface, flat on a dark comparison of simple, easy to observe understand. Light source irradiation above the left side of the cube, up nearly vertical in the presence of light and gloss, tilted to t

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