Assertion: natural gas | /r/HasProperty | unconventional
Facets:
value: sometimes
type: TEMPORAL
value: generally
type: DEGREE
Source sentences:
text: Composed mostly of methane, natural gas is generally considered either conventional or unconventional, depending on where it’s found underground.
text: This natural gas is referred to as shale gas or tight gas, and it is sometimes called unconventional natural gas.