( ( ( Gas Form ) ( of Matter ) ) - )
(ROOT (NP (NP (NNP Gas) (NNP Form)) (PP (IN of) (NP (NNP Matter))) (: -)))
Gas Form of Matter -
(ROOT (S (NP (DT A) (NN gas)) (VP (VBZ assumes) (NP (NP (DT the) (NN shape)) (PP (IN of) (NP (PRP$ its) (NN container))))) (. .)))