Assertion: boa constrictor's teeth | /r/CapableOf | fold into the mouth
Facets:
value: in use
type: TEMPORAL
value: backward
type: MANNER
Source sentences:
text: In non-venomous, constrictor snakes, the teeth are stationary; in snakes with long (grooved) fangs, the teeth fold backward into the mouth when not in use -- otherwise, the snake would puncture the bottom of its own mouth.