幸福婚姻和痛苦婚姻的区别...在于大约十个持续的愚蠢或善良行为，取决于方向。
Nature tends to produce constancy in all her works, but she does not always succeed.
The best way to understand labor markets is to look at real-world data, not just theoretical models.
理解劳动力市场的最佳方式是观察现实数据，而不仅仅是理论模型。