Assertion: mirror's surface | /r/HasProperty | flat
Facets:
value: perfectly
type: DEGREE
Source sentences:
text: Their reflective surfaces may be either flat or curved.
text: If the surface of a mirror is perfectly flat (what's known as a plane mirror ), what you see in the glass is a reasonable approximation to what's really there
text: A mirror is flat or curved surface usually produced of glass that has had a reflective coating applied to it.