( ( ( ( ( The ( poison gas ) ) ( ( burns off ) ( in ( the atmosphere ) ) ) ) and ) ( ( the Earth ) ( is saved ) ) ) . )
(ROOT (S (S (NP (DT The) (NN poison) (NN gas)) (VP (VBZ burns) (PRT (RP off)) (PP (IN in) (NP (DT the) (NN atmosphere))))) (CC and) (S (NP (DT the) (NN Earth)) (VP (VBZ is) (VP (VBN saved)))) (. .)))
The poison gas burns off in the atmosphere and the Earth is saved.
(ROOT (S (NP (JJ Volcanic) (NNS gases)) (VP (VBP helpe) (S (VP (TO to) (VP (VB form) (NP (DT the) (NN atmosphere)) (PP (IN on) (NP (NN earth))))))) (. .)))