( ( Nuclear energy ) ( ( is ( ( the energy ) ( that ( ( holds together ) ( ( the nuclei ) ( of atoms ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Nuclear) (NN energy)) (VP (VBZ is) (NP (NP (DT the) (NN energy)) (SBAR (WHNP (WDT that)) (S (VP (VBZ holds) (PRT (RP together)) (NP (NP (DT the) (NN nuclei)) (PP (IN of) (NP (NNS atoms))))))))) (. .)))
Nuclear energy is the energy that holds together the nuclei of atoms.
(ROOT (S (NP (NN Bond) (NN energy)) (VP (VBZ holds) (NP (NNS atoms)) (ADVP (RB together))) (. .)))
Bond energy holds atoms together.