Assertion: female mule | /r/CapableOf | produce offspring
Facets:
value: on rare occasions
type: TEMPORAL
value: very rarely
type: DEGREE
Source sentences:
text: A few female mules have produced offspring, but only when mated with a horse or donkey.
text: And just as female mules and hinnies only very rarely produce offspring the same appears to be true of zebroids.
text: Female mules have been known, on rare occasions, to produce offspring when mated to a horse or donkey, although this is extremely uncommon.