石臼是一种用石头做的工具，古时候人们用它来把米、麦子或豆子磨成粉。

A 石臼 is a tool made of stone that people in ancient times used to grind rice, wheat, or beans into powder.

现在很少有人用石臼了，但在一些农村还能看到。

Nowadays, few people use a 石臼, but it can still be seen in some rural areas.