( Carbon ( ( forms ( ( the skeleton ) ( of ( all ( organic molecules ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Carbon)) (VP (VBZ forms) (NP (NP (DT the) (NN skeleton)) (PP (IN of) (NP (DT all) (JJ organic) (NNS molecules))))) (. .)))
Carbon forms the skeleton of all organic molecules.
(ROOT (S (NP (DT The) (NN element) (NN carbon)) (VP (VBZ is) (ADJP (JJ present) (PP (IN in) (NP (DT all) (JJ organic) (NNS molecules))))) (. .)))
The element carbon is present in all organic molecules.