( ( Heat ( makes ( air expand ) ) ) ( , ( cold ( ( makes ( air contract ) ) . ) ) ) )
(ROOT (S (S (NP (NNP Heat)) (VP (VBZ makes) (S (NP (NN air)) (VP (VB expand))))) (, ,) (NP (JJ cold)) (VP (VBZ makes) (NP (NN air) (NN contract))) (. .)))
Heat makes air expand, cold makes air contract.
(ROOT (S (NP (NP (DT The) (NN liquid)) (PP (IN in) (NP (DT a) (NN thermometer)))) (VP (VP (VBZ expands)) (CC or) (VP (VBZ contracts) (S (VP (TO to) (VP (VB respond) (PP (TO to) (NP (NN heat) (CC or) (NN cold)))))))) (. .)))