钢琴上从C到下一个C是一个八度。

On the piano, from C to the next C is an ___octave.

这首歌的高潮部分需要跨越几个八度音阶。

The climax of this song requires singing across several ___octaves.

钢琴上的这个音符比另一个高八度。

This note on the piano is an ___octave higher than the other one.