All who joy would win must share it. Happiness was born a twin.

学习数学的最好方法就是做数学。

经济学的未来在于弥合理论与实践之间的差距。

自然界的普遍法则大多不是直接感知的对象。

You don’t build a business—you build people—and then people build the business.

The war on coal is a war on the American worker.