average grading

• 平均粒度

average grading的用法和样例：

例句

1. Index based on coal properties shows that coal properties principally affect the forming of big FA and the average volume size of FA, and less to small FA.
   飞灰粒度特性综合指数表明，煤质主要影响到粗粒度飞灰的形成及飞灰的体积平均粒度，而对细粒度飞灰的形成影响很小。