Assertion: circulatory system's vein | /r/MadeOf | one-way venous valves
Facets:
Source sentences:
text: The veins themselves contain one-way venous valves which work in pairs.
text: The veins themselves contain one-way venous valves which work in pairs.
text: The veins themselves contain one-way venous valves which work in pairs.
text: The veins themselves contain one-way venous valves which work in pairs.