脸的

For example, OpenGL does not directly support drawing a concave polygon.

举例来说，OpenGL的不直接支持画凹多边形。

The paper analysed the characteristics of noise pollution in cement plant harm to human health, and emphasized the control theory and detail method of noise from ball mill and fan, fianlly put forward the control measure.

文章分析了水泥厂噪声污染的特点，阐述了噪声对人健康的危害，重点分析了球磨机和风机噪声的控制原理和具体方法，提出了综合治理的措施。