油磨刀石

例句：

1. 1. He used a piece ofwood as an oilstone to sharpenhis knife.
   他用一块木头作为油磨刀石来磨他的刀。
2. 2. The oldman had been using this oilstone foryears, and it was still very sharp.
   这位老人已经用这个油磨刀石很多年了，它仍然非常锋利。
3. 3.The chef carefully selected the right oilstonefor each cutting task.
   厨师仔细地为每个切割任务选择了正确的油磨刀石。