For example, if you started here and you did all this and you came back here, the average velocity would be zero, because you start and end at the same value of x, you get something; 0 divided by time will still be 0.

例如,如果你从这里开始运动,经过这个过程又回到这里,平均速度就是0,因为初态和末态的位移相同,你得到了什么呢,0除以时间还是0

耶鲁公开课 - 基础物理课程节选

So, when the value of the average valence electron energy lies between 11 eV and 13 eV, we have these elements that are neither fish nor fowl, and you'll see in a little bit their unique electrical properties.

所以，当平均价电子能,在11eV到13eV之间时，这些元素介于金属和非金属之间，你们将进一步,看到它们独特的电性质。

麻省理工公开课 - 固态化学导论课程节选