They're efficient enough that you have to work hard to find opportunities, but not perfectly.

如果你付出足够的努力,还是能发现机会,所以市场并不完全有效

耶鲁公开课 - 金融市场课程节选

If you put in the effort, the grade will reflect that."

如果你付出了努力，评级结果则会将之反映出来“

耶鲁公开课 - 死亡课程节选