工具变量的美妙之处在于它们让我们以新的视角看世界。

Man, unlike any other thing organic or inorganic in the universe, grows beyond his work, walks up the stairs of his concepts, emerges ahead of his accomplishments.

Every challenge in livestock farming is an opportunity to innovate.

不要因为结束而哭泣，微笑吧，为你的曾经拥有。

财产权确实是人类的一项权利，与自由一样真实。