Anyone who has kept an aquarium of gold fish, for example, knows that he either has to keep changing the water in the tank as the fish use up the oxygen in it, or he can &quot;build in&quot; the oxygen supply, as you said, by putting plants in the tank.
(the fish; use up; the oxygen in it) (he; can quot; ) (he; to keep; changing the water in the tank) Context(he to keep,List([70, 91))):(he; to keep changing; the water) (you; said; )
he to keep,List([70, 91))
the fish he he he you
use up can quot to keep to keep changing said
the oxygen in it
changing the water in the tank
the water