( ( 173.273 Sulfur ) ( trioxide . ) )
(ROOT (S (NP (CD 173.273) (NN Sulfur)) (VP (VBP trioxide)) (. .)))
173.273 Sulfur trioxide.
(ROOT (S (NP (NNP Sulfur)) (VP (MD can) (VP (VB combine) (PP (IN with) (NP (NN oxygen))) (S (VP (TO to) (VP (VB produce) (NP (NN sulfur) (NN trioxide))))))) (. .)))