"Randomized experiments are the gold standard for causal inference, but they are not always feasible."

赏赐并不能让人欢喜，责罚也不能让人畏惧。 

写作是一种祈祷形式。

我们都知道，儿童发展的时期是一生最重要的时期。道德的营养不良和精神的中毒对人的心灵的危害正如身体的营养不良对于身体健康的危害一样。所以，儿童教育是人类展重要的一个问题。

在家听从父亲的，出嫁则服从丈夫。

The greatest happiness of life is the conviction that we are loved; loved for ourselves, or rather, loved in spite of ourselves.

Man is the only creature who refuses to be what he is.

I think prime numbers are like life. They are very logical but you could never work out the rules, even if you spent all your time thinking about them.