有时候，正是那些没人对他们抱有任何期望的人，做出了没人能想象到的事。

The Liskov Substitution Principle is a fundamental concept in object-oriented programming, ensuring that derived classes can be used in place of their base classes without altering the correctness of the program.

译文：清贫的生活，对读书人来说，就是顺境；节俭的日子，对种田人来说，就是丰收的年岁。赏析：读书要耐得住寂寞。清贫的生活能排除浮华奢糜之事，否则只会扰乱身心与学业。节俭是良好的美德，也是人类生存之需要。如果平常俭约，有所积蓄，即使是收成很差，也能丰衣足食。假如不懂得节俭，泿费粮食，即使年年丰收，也会缺衣少食。

The most effective way to destroy people is to deny and obliterate their own understanding of their history.

The past is not dead; it is not even past.