( One ( ( can ( ( have ( ( more ( than one ) ) parabola ) ) ( because ( ( isotopes ( with ( ( ( ( an ( even number ) ) ( of protons ) ) and ) ( ( an ( even number ) ) ( of neutrons ) ) ) ) ) ( are ( more ( stable ( than ( isotopes ( with ( ( ( ( an ( odd number ) ) ( of neutrons ) ) and ) ( ( an ( odd number ) ) ( of protons ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP One)) (VP (MD can) (VP (VB have) (NP (QP (JJR more) (IN than) (CD one)) (NNS parabola)) (SBAR (IN because) (S (NP (NP (NNS isotopes)) (PP (IN with) (NP (NP (NP (DT an) (JJ even) (NN number)) (PP (IN of) (NP (NNS protons)))) (CC and) (NP (NP (DT an) (JJ even) (NN number)) (PP (IN of) (NP (NNS neutrons))))))) (VP (VBP are) (ADJP (RBR more) (JJ stable) (PP (IN than) (NP (NP (NNS isotopes)) (PP (IN with) (NP (NP (NP (DT an) (JJ odd) (NN number)) (PP (IN of) (NP (NNS neutrons)))) (CC and) (NP (NP (DT an) (JJ odd) (NN number)) (PP (IN of) (NP (NNS protons)))))))))))))) (. .)))
One can have more than one parabola because isotopes with an even number of protons and an even number of neutrons are more stable than isotopes with an odd number of neutrons and an odd number of protons.
(ROOT (S (NP (NP (NNP Nuclei)) (PP (IN with) (NP (NP (RB even) (NNS numbers)) (PP (IN of) (NP (NP (NNS protons)) (, ,) (NP (NNS neutrons)) (, ,) (CC or) (NP (DT both))))))) (VP (VBP are) (ADJP (RBR more) (JJ likely) (S (VP (TO to) (VP (VB be) (ADJP (JJ stable))))))) (. .)))