As time increases, the angle increases and we can ask, "How long does it take for the particle to come back to the starting point?"

这个角度随着时间在增加,我们会问,"质点需要多长时间,才能转到起点"

耶鲁公开课 - 基础物理课程节选

" And-- "How long are you going to stay happy for?"

你们的快乐会持续多久“

哈佛公开课 - 幸福课课程节选

" And-- "How long are you going to be devastated for?"

那你们会痛苦多久“

哈佛公开课 - 幸福课课程节选