請問24複音口琴係吹上面果行定下面?

Generally, you need to blow both the upper the lower part.

There are many different and difficult techniques for playing harmonica.

e.g. 雙音, 連音, Trio, 震音,

If you play songs with quich tempo, it will also be chanllenging as you have to move quickly and accurately.

On the whole, playing harmonica is not difficult but playing it well is difficult.