( ( ( oxidizer ( A chemical ) ) ( ( ( that ( readily ( yields oxygen ) ) ) or ) ( that ( vigorously ( promotes ( ( ( oxidation reactions ) or ) combustion ) ) ) ) ) ) . )
(ROOT (S (VP (VB oxidizer) (NP (DT A) (NN chemical)) (SBAR (SBAR (WHNP (WDT that)) (S (ADVP (RB readily)) (VP (VBZ yields) (NP (NN oxygen))))) (CC or) (SBAR (WHNP (WDT that)) (S (ADVP (RB vigorously)) (VP (VBZ promotes) (NP (NP (NN oxidation) (NNS reactions)) (CC or) (NP (NN combustion)))))))) (. .)))
oxidizer A chemical that readily yields oxygen or that vigorously promotes oxidation reactions or combustion.
(ROOT (S (NP (NNP Combustion) (NN reaction)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN substance)) (VP (VBZ reacts) (ADVP (RB quickly)) (PP (IN with) (NP (NN oxygen))))))) (. .)))