Assertion: warthog's tusk | /r/CapableOf | rub against upper tusks
Facets:
value: repeatedly
type: TEMPORAL
value: every time the warthog opens
type: TEMPORAL
Source sentences:
text: Every time the warthog opens and closes its mouth, the bottom tusks rub against the upper tusks, sharpening them into razor-sharp points.
text: The snout is long, bearing two pairs of tusks (modified canine teeth), which they use to dig and as defensive weapons; the smaller tusks in the lower jaw rub repeatedly against the upper tusks when the mouth is closed, giving them a razor edge and a nasty bite when defending itself.