有时候问题很复杂，但答案却很简单。
Sometimes the questions are complicated and the answers are simple.
数学不仅仅是关于数字、方程、计算或算法：它是关于理解的。
States are rational actors, and they will always act in their own self-interest.
Great brands are built one satisfied customer at a time.
In mathematics, you don't understand things. You just get used to them.
If you want to be given everything, give everything up.