Electric motors are relatively efficient energy users so perhaps a fan, near the ceiling, forcing warm air downwards (the rising of hot air is a spontaneous process that can be reversed only by energy input -
(energy users; forcing; warm air downwards) (a spontaneous process; can be reversed; ) (the rising of hot air; is; a spontaneous process that can be reversed only by energy input) Context(the rising of hot air is,List([118, 142))):(Electric motors; are; relatively efficient)
the rising of hot air is,List([118, 142))
energy users a spontaneous process the rising of hot air Electric motors
forcing can be reversed is are
warm air downwards
a spontaneous process that can be reversed only by energy input
relatively efficient