Because if they work any harder than that, then the other person is just going to slack off instead.

因为我们知道如果自己超额完成工作,其他人就可以少做点工作了

耶鲁公开课 - 博弈论课程节选

How do you manage your time to study and do other kinds of work?

你怎么利用时间学习和做其他工作？

再没时间也要挤出来 - SpeakingMax英语口语达人

Americans spend the most time out of any other people in the world volunteering in average four hours a week, volunteering outside their job which may also have a social objective more than any other people in the world.

比其他任何人所花的时间都多,平均每周有四个小时做志愿者的工作，做与自身工作无关的善事,他们比世界上其他人更具社会目标。

哈佛公开课 - 幸福课课程节选