相关系数的可能误差不是可以从第一原理推导出来的东西，而是必须通过经验找到的。

The true cost of coal isn't just in its price, but in how we manage its consequences.

The most successful products are often the simplest solutions to everyday problems.

Success is doing what you want to do, when you want, where you want, with whom you want, as much as you want.

最危险的事情是在情况不妙时装作一切正常。

如果你不偶尔失败，说明你不够努力。