Assertion: bass clarinet's key | /r/HasProperty | one
Facets:
Source sentences:
text: opening and closing of keys must be quick - that is especially critical in the case of the open keys - the ones that are opend by pressing with a finger and closed by a spring pressing the pad back onto the hole.
text: In addition, older bass clarinets have two register keys, one for middle D♯ and below, the other for middle E and higher.