Assertion: eye's lens | /r/HasProperty | easy to make
Facets:
value: by one spherical surface
type: OTHER
value: very
type: DEGREE
value: by a plane spherical surface
type: MANNER
Source sentences:
text: In general, a lens is made of glass and is bounded by two regular curved surfaces; or by one spherical surface and a plane spherical surface is very easy to make.