Never use a credit card for credit. The only kind of credit， or debt， that is acceptable is debt to acquire something whose exchange value is extremely likely to increase， like in a home. The exchange value of most things diminishes or vanishes the moment you purchase them. Don’t be in debt to losers.

我从没有爱过这世界，它对我也一样。

数学中最重要的是提出正确的问题。