求翻译：物体在光线照射作用下，根据其自身结构转折关系将会呈现出来的不同黑白灰关系，而这种黑白灰关系是由物体各个面与主光源的角度不同所导致的。这只是我们视觉的感受，如果没有光线，物体将不可见。不同的物体具有不同的明暗，同样，光源角度及强度的变化也会使同一个物体呈现出不同的明暗层次。所以设计素描的造型训练，除了把形体、结构画准外，明暗处理是一个很重要的因素。主要是借助描绘物体的明暗关系，来充分表现物象的固有色调、质量感、立体空间效果等 .是什么意思？

When exposed to light under the action of the object, according to its own structure, the relationship will turn black and white presentation of the different gray between black and white ash and this relationship is different from the object surface and the angle of the main light source due to the

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The object under the light illumination function, relates the different black lime relations according to its own structure transition which will be able to present, but this kind of black lime relations will be each and the host photosource angle different cause b

Objects under the action of light, turning point in relations will be presented according to its own structure of different black and white ash, but this relationship between black and white ash is composed of objects, each individual face the result of a different angle than the main light source.