We have 266, as some of you might know who saw me counting ping-pong balls the other day in office hours.

看到了这些发泡胶球事实上,可以当作单层金原子核,我们有266个乒乓球。

麻省理工公开课 - 化学原理课程节选

Those of you who have your ping-pong balls can now begin the experiment.

好，我们会到这边来把球给你们,已经拿到球的同学就可以开始试验了。

麻省理工公开课 - 化学原理课程节选