With the sun, the air contained in the sac of the pollen heats and expands and the balloon floats and rises in the air.
(the air; contained; in the sac of the pollen) (the air contained in the sac of the pollen; heats; ) (the air contained in the sac of the pollen; expands; )
the air the air contained in the sac of the pollen the air contained in the sac of the pollen
contained heats expands
in the sac of the pollen