As the grinding goes on, the pieces get small. Over a long time, tiny grains of sand are made.
在风浪的冲刷下，这些碎粒被磨得越来越小，很久以后就形成了很小的沙粒。
2
Researchers surmise that over billions of years the debris should collide, grinding the KBO-type objects down to ever smaller pieces that were not part of the original Kuiper Belt population.
研究人员推测数这些碎块经过数十亿年的互相碰撞，柯伊伯型天体磨得更碎，柯伊伯带原始状态不再。
3
If so, the mortgage crunch will be a grinding drag on America's economy; one that unfolds over several years, hitting some people and some regions hard, but not, in itself, a macro-economic disaster.