Assertion: rock | /r/HasProperty | developed in 1950
Facets:
Source sentences:
text: Rock and roll is a form of rock music developed in the 1950s and 1960s.
text: Rock and roll is a form of rock music developed in the 1950s and 1960s.
text: Rock and roll is a form of rock music developed in the 1950s and 1960s.