( ( A gas ) ( ( is ( matter ( that ( has ( ( ( no ( definite ( ( shape or ) volume ) ) ) , ) ( such ( as oxygen ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN gas)) (VP (VBZ is) (NP (NP (NN matter)) (SBAR (WHNP (WDT that)) (S (VP (VBZ has) (NP (NP (DT no) (JJ definite) (NN shape) (CC or) (NN volume)) (, ,) (PP (JJ such) (IN as) (NP (NN oxygen))))))))) (. .)))
A gas is matter that has no definite shape or volume, such as oxygen.
(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)))) (. .)))