So this is equal to m minus 1, plus mn minus m.

所以这等于 m 减 1，加上 mn 减 m。

Then we have a schwa again, but when the schwa is followed by n, we don't really hear it, mn, mn, mn.

然后我们又有一个 schwa，但是当 schwa 后面跟着 n 时，我们并没有真正听到它， mn，mn，mn。

This is equal to mn minus 1 degrees of freedom, which is exactly the total degrees of freedom we had for the total sum of squares.

这等于 mn 减去 1 个自由度，这恰好是总平方和的总自由度。