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。

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And this whole note obviously can be subdivided into two half notes and each of the half notes into two quarter notes each of these quarter notes into two eighth notes, and so on.

这个全音符,很明显,可以再分为两个半音符,每个半音符又可以再细分为两个四分之一音符,每个四分之一音符可以再分为两个八分之一音符,等等

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