And in fact, one of the lessons you may already be realizing with P sets is that things seem to take twice, three times, four times longer than you actually might think.

从习题集中你可能已经得出的一个教训就是,程序所花的实际时间往往是你开始以为的两倍，三倍，四倍甚至更长。

哈佛公开课 - 计算机科学课程节选

Or perhaps Chinese on Monday, Wednesdays, and Fridays and Thai on Saturdays and Sundays and spending two hours in the afternoon doing math and three hours in the morning doing philosophy.

或周一三五吃中餐,周六日吃泰国菜,下午花两小时研究数学,上午三小时思考哲学，统统没有用。

耶鲁公开课 - 死亡课程节选