You can always juice sales by going down-market， but it's hard to go back upmarket.
当市场下跌时，你轻易的将好东西打折变卖，但是一旦市场向上，再想买回来，难之又难。
预测未来的最好方法就是去创造它。
The most expensive thing in the world is trust. It can take years to earn and just a matter of seconds to lose.
谎言重复千遍就是真理。
Most man rather deny the turth than face it.
函数是一种对应规则，通过它当给定任何东西（作为参数）时，可以获得另一个东西（该参数的函数值）。