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 earth gives us coal; our duty is to give back stewardship.
Medicine is my lawful wife, and literature is my mistress.
I wish I could write as mysterious as a cat.
我们总是以诗般的语言刻画自己在青春的罅隙中的那般狼狈。