The grain size differs obviously with the time of ball milling and it reaches the smallest value when been ball milled for 15~20 hours. The grain size also grows when annealed at certain temperature.

结果表明在行星球磨方法下，球磨15到20小时材料晶粒达到最小，在一定温度下退火之后材料晶粒长大。

youdao

The relative size of these components differs greatly between countries and over time, and can be particularly important in the level and growth of real living standards in the poorest countries.

ECONOMIST: Rich man, poor man

The vaccine differs from birth control pills not only in the size of its benefit to recipients, but also because the vaccine benefits more than simply the person who receives it.

FORBES: The Pill, the Pox and the Limits of Religious Freedom