解释：货卖完了才知道不足，是由于不懂得计量；事情结束了才知道有余，是由于不懂得调节。
The beauty of a mathematical idea is that it can be shared and understood across cultures and time.
Sleep， those little slices of death — how I loathe them.
我们的故事是我们的生存，我们的抵抗，我们的希望。
Never stop learning because the world never stops changing.
