( ( ( ( Oxygen , ) ( a gas ) ) , ) ( ( is ( ( released ( into ( the atmosphere ) ) ) ( by ( growing plants ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Oxygen)) (, ,) (NP (DT a) (NN gas)) (, ,)) (VP (VBZ is) (VP (VBN released) (PP (IN into) (NP (DT the) (NN atmosphere))) (PP (IN by) (NP (VBG growing) (NNS plants))))) (. .)))
Oxygen, a gas, is released into the atmosphere by growing plants.
(ROOT (S (NP (NN Oxygen) (NN gas)) (VP (VBZ is) (VP (VBN given) (PRT (RP off)) (PP (IN by) (NP (NNS plants))))) (. .)))