Natural experiments can provide valuable insights into economic questions.
自然实验可以为经济问题提供有价值的见解。
The lion doesn't care about the opinions of the sheep.
破坏东西比创造它们容易得多。
我不怕死，我怕不去尝试。
Stay focused on what you can control, and don’t waste energy on what you can’t.
相同的事物即使与相同的主体结合，也不会产生相同的效果。