Assertion: poem | /r/ObjectUse | used in 18th century
Facets:
value: so often
type: TEMPORAL
Source sentences:
text: A rhymed pair of lines of iambic pentameter make a heroic couplet, a verse form which was used so often in the 18th century that it is now used mostly for humorous effect (although see Pale Fire for a non-trivial case).