Assertion: heart valve | /r/CapableOf | make sure
Facets:
Source sentences:
text: The four heart valves make sure that blood always flows freely in a forward direction and that there is no backward leakage.
text: The four heart valves make sure that blood always flows freely in a forward direction and that there is no backward leakage.
text: The four heart valves make sure that blood always flows freely in a forward direction and that there's no backward leakage.