( ( ( ( Jupiter ( , ( Saturn ( , ( Uranus , ) ) ) ) ) and ) Neptune ) ( ( ( are primarily ) ( ( hydrogen and ) helium ) ) . ) )
(ROOT (S (NP (NP (NNP Jupiter) (, ,) (NNP Saturn) (, ,) (NNP Uranus) (, ,)) (CC and) (NP (NNP Neptune))) (VP (VBP are) (ADVP (RB primarily)) (NP (NP (NN hydrogen)) (CC and) (NP (NNP helium)))) (. .)))
Jupiter, Saturn, Uranus, and Neptune are primarily 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))))) (. .)))