( ( Metallic solids ) ( ( are ( repeating ( units ( ( made up ) ( of ( metal atoms ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Metallic) (NNS solids)) (VP (VBP are) (VP (VBG repeating) (NP (NP (NNS units)) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (NN metal) (NNS atoms))))))) (. .)))
Metallic                        solids are repeating units made up of metal atoms.
(ROOT (S (NP (JJ Metallic) (NNS solids)) (VP (VBP are) (VP (VBN composed) (ADVP (RB entirely)) (PP (IN of) (NP (JJ metallic) (NNS atoms))))) (. .)))