( ( ( ( ( The ( subatomic particles ) ) , ) ( protons ( , ( ( neutrons and ) electrons ) ) ) ) , ) ( ( combine ( to ( form atoms ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ subatomic) (NNS particles)) (, ,) (NP (NNS protons) (, ,) (NNS neutrons) (CC and) (NNS electrons)) (, ,)) (VP (VBP combine) (S (VP (TO to) (VP (VB form) (NP (NNS atoms)))))) (. .)))
The subatomic particles, protons, neutrons and electrons, combine to form atoms.
(ROOT (S (NP (NP (DT The) (NN number)) (PP (IN of) (NP (NNS neutrons)))) (VP (MD can) (VP (VB vary) (PP (IN between) (NP (NP (NNS atoms)) (PP (IN of) (NP (DT the) (JJ same) (NN element))))))) (. .)))