两个物体的相互作用力总是大小相等，方向相反，同时出现或消失且作用于同一直线上。
To every action there is always opposed an equal reaction； or， the mutual actions of two bodies upon each other are always equal， and directed to contrary parts.
That's the only trouble with being a dog…they never tell you anything.
Customer loyalty is earned, not bought.
我们唯一需要害怕的就是害怕本身。
安全必须始终是采矿作业的首要任务。
The poor are not irrational; they are just as rational as anyone else, but they operate under very different constraints.
一本书是作者与读者之间无限的对话。
