A corporation is an entity that could be sued or could lose more money than it's worth, but the value of a corporation can never fall below zero to the investors because the investors are not liable for the mistakes of the corporation.

公司是一个实体,它可能被起诉,或者亏损额超过了自身的价值,但是对于投资者而言,公司的价值永远不会小于零,因为投资者对公司的过失,不负有责任

耶鲁公开课 - 金融市场课程节选

It looks like we hit zero, but we actually don't remember that we never go all the way to zero, so there's these little points if we were to look really carefully at an accurate probability density plot, And then, for example, how many nodes do we have in the 3 s orbital?

但其实没有，记住，我们永远不会到零,如果我们，在概率密度图上,非常细致的看这些点的话,它永远不会到零，在3s轨道里，有多少个点呢？，2个，正确？

麻省理工公开课 - 化学原理课程节选