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。
Every mathematical problem has a solution; sometimes it just takes time to find it.
The measure of a good book is determined by how much it disturbs and troubles its reader.
Innovation in extraction technology is meaningless if it doesn't prioritize environmental sustainability.