There are no hard distinctions between what is real and what is unreal, nor between what is true and what is false. A thing is not necessarily either true or false; it can be both true and false.
在数学中，我们常常追求优雅和简洁，但在计算机科学中，我们还必须考虑实用性和效率。
城市是一个活生生的东西，总是在变化，又总是一样。