现实总是比我们对它的任何想法都更加丰富。
The Liskov Substitution Principle is a fundamental concept in object-oriented programming, stating that objects of a superclass should be replaceable with objects of a subclass without affecting the correctness of the program.
真正的美国发现还在我们面前。我们精神、我们人民、我们强大而不朽的土地的真正实现,尚未到来。