每一个数学问题都是通向新理解世界的窗口。
Every mathematical problem is a window into a new world of understanding.
种荆棘会得到刺，种桃李会得到树荫。比喻善恶有报
Coal miners are the unsung heroes of America's industrial strength.
一个人若不付出一些无知的代价，就永远不会幸福。