Assertion: harmonica's sound | /r/CapableOf | play only oneparticular note
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Source sentences:
text: To explain why harmonica position are so important, it is necessary to illustrate a fundamental difference between playing a harmonica and playing an instrument like a keyboard: when playing a keyboard we always use different keys to play different scales; however, when you press a key on a keyboard you already know what sound is going to be produced because each key is only ever tuned to play one (and only one) particular note.