( They ( ( breathe ( nitrogen ( instead ( of oxygen ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBZ breathe) (NP (NP (NN nitrogen)) (PP (RB instead) (IN of) (NP (NN oxygen))))) (. .)))
They breathe nitrogen instead of oxygen.
(ROOT (S (NP (NNP Nitrogen) (, ,) (NNP oxygen) (CC and) (NNP argon)) (VP (VBP are) (NP (NP (DT the) (CD three) (JJS most) (JJ common) (NNS elements)) (PP (IN in) (NP (NP (DT the) (NN air)) (SBAR (S (NP (PRP we)) (VP (VB breathe)))))))) (. .)))