The air is heated by the burner and the expanding air causes the balloon to rise through the denser, cooled air.
(The air; is heated; by the burner) (the expanding air; causes; the balloon to rise through the denser) Context(the expanding air causes,List([36, 60))):(the balloon; to rise; through the denser)
the expanding air causes,List([36, 60))
The air the expanding air the balloon
is heated causes to rise
by the burner
the balloon to rise through the denser
through the denser