1.lit. don't worry about not knowing goods, but about comparing them (proverb)2.fig. goods' (or person's) true value can only be determined through comparison
1.If you work at it hard enough, you can grind an iron bar into a needle.2.cf idiom 磨杵成针, to grind an iron bar down to a fine needle (idiom); fig. to persevere in a difficult task3.to study diligently