It is this problem of the initial wear taking off the hills and hollows which makes workshop engineers so particular in obtaining the smoothest possible finish on motor and aeroplane cylinders and pistons, on high speed bearings, and so on.

• 正是一开始接触面之间高低不平的地方要被磨平这个问题，使车间工程师强调，要求在加工汽车和飞机的汽缸与活塞以及高速轴承等时，力争达到尽可能高的表面光洁度。