( However ( , ( ( a gas ) ( ( is ( ( a substance ) ( ( with neither ) ( ( ( a ( definite shape ) ) nor ) volume ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB However)) (, ,) (NP (DT a) (NN gas)) (VP (VBZ is) (NP (NP (DT a) (NN substance)) (PP (IN with) (ADVP (DT neither)) (NP (NP (DT a) (JJ definite) (NN shape)) (CC nor) (NP (NN volume)))))) (. .)))
However, a gas is a substance with neither a definite shape nor volume.
(ROOT (S (NP (NP (DT The) (NN gas) (NN form)) (PP (IN of) (NP (NN matter)))) (VP (VBZ has) (NP (NP (ADVP (DT neither)) (DT a) (JJ definite) (NN shape)) (CC nor) (NP (DT a) (JJ definite) (NN volume)))) (. .)))