Assertion: green chalkboard | /r/MadeOf | porcelain enamel
Facets:
value: on a steel base
type: LOCATION
value: generally
type: DEGREE
Source sentences:
text: Green chalkboards, generally made of porcelain enamel on a steel base, first appeared in the 1960s.
text: Green chalkboards, generally made of porcelain enamel on a steel base, first appeared in the 1960s.
text: Green chalkboards, generally made of porcelain enamel on a steel base, first appeared in the 1960s.