In fact, there are some very old books that show this as the average, the sum divided by two arithmetic mean, but the modern practice is to use the geometric mean.

事实上，一些很老的书籍上,平均的定义就是算数意义的，总的来说被分为两种算数意义，但现代我们多用几何意义。

麻省理工公开课 - 固态化学导论课程节选

Okay, so I'd like to end with a little show of diet books and diet plans.

这节课将以展示一些,减肥书籍和减肥计划作为结束

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选