学习数学的最好方法就是做数学。
The best way to learn mathematics is to do mathematics.
如果你面对去年的自己不感到尴尬的话，你目前可能学习得不够努力。
因果推理需要仔细思考分析背后的假设。
If you loan someone $20 and you never see them again. That makes it worth $20.
我不相信运气，但我相信为事物赋予价值。