Assertion: skeletal system's bone | /r/HasProperty | hollow
Facets:
Source sentences:
text: The bones of birds are hollow, light and create a streamlined body adapted for flight.
text: Osteoclasts' role in diameter growth of bones is to remove some bone tissue from the inside of the bone (bones are hollow).
text: Bones of birds are hollow which makes them light-weighted while internal struts or cross walls make them strong.