diameter of tiny hole

• 微孔直径

diameter of tiny hole的用法和样例：

例句

1. When the reaction time elapsed, the changes of the pore surface and average pore diameter become mild and the pore volume reduced drastically and then remain unchanged.
   反应时间增长后，小孔表面积与平均小孔直径变化趋缓，而小孔体积则大幅下滑再维持稳定。