n.磨刀石；砂轮
Our factory produces grindstone. 我们工厂生产磨刀石。
They ground the knife on a grindstone. 他们在磨刀石上磨刀子。
It's a pity I have to get back to the grindstone. 遗憾的是我不得不回去工作。
The teacher believed in hard work and always keep our nose to the grindstone. 老师提倡勤奋，而且也总是要我们埋头读书。
I always admire men, even the dullest, who know their job and put their noses to the grindstone. 我一向敬重那些有专长且做事勤奋不懈的人，包括那些最没情趣的人。
