Assertion: fox's den | /r/HasProperty | a network of tunnels
Facets:
value: often
type: TEMPORAL
Source sentences:
text: Adult Arctic foxes raise their pups in these underground dens, which are often a network of tunnels covering an area the size of a football field!
text: The arctic fox is found in polar forests where it lives in dens that are actually a network of tunnels, some of which are underground.