So you can imagine a bead with a wire going through it and the bead can only slide back and forth.

你可以想象一个穿在绳子上的珠子,小珠只能前后滑动

耶鲁公开课 - 基础物理课程节选

We were going to have a clicker slide on how many bounced back but it looks like we're having a little technical difficulty with that.

发生背散射，球被弹回来了的,同学请你们站起来,让我算算。

麻省理工公开课 - 化学原理课程节选