( ( Like ( the others ) ) ( , ( Saturn ( ( ( ( has ( a ( rocky core ) ) ) but ) ( ( is primarily ) ( composed ( of ( ( ( ( ( light elements ) , ) ( mostly hydrogen ) ) and ) helium ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN Like) (NP (DT the) (NNS others))) (, ,) (NP (NNP Saturn)) (VP (VP (VBZ has) (NP (DT a) (JJ rocky) (NN core))) (CC but) (VP (VBZ is) (ADVP (RB primarily)) (VP (VBN composed) (PP (IN of) (NP (NP (JJ light) (NNS elements)) (, ,) (NP (RB mostly) (NN hydrogen)) (CC and) (NP (NNP helium))))))) (. .)))
Like the others, Saturn has a rocky core but is primarily composed of light elements, mostly hydrogen and helium.
(ROOT (S (NP (NNP Saturn)) (VP (VBZ is) (VP (VBN made) (ADVP (RB mostly)) (PP (IN of) (NP (NN helium) (CC and) (NN hydrogen))))) (. .)))