例句與造句

1. Supercomputers grind away for weeks on these problems,
2. Grind away for at least two or three minutes; the best pros in Rio, I found, keep at it for five minutes.
3. In the next room, a noisy machine grinds away for 20 hours, mixing the porcelain _ her own three-part recipe worked out years ago at the Massachusetts Institute of Technology.
4. It's difficult to find grind away for in a sentence. 用grind away for造句挺難的