( ( All ( natural carbon ) ) ( ( occurs ( in ( ( ( three isotopes...carbon-12 ) and ) ( ( ( -13 ( , ( non-radioactive ( , ( and carbon-14 ) ) ) ) ) , ) ( a ( radioactive isotope ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT All) (JJ natural) (NN carbon)) (VP (VBZ occurs) (PP (IN in) (NP (NP (CD three) (NNS isotopes...carbon-12)) (CC and) (NP (NP (CD -13) (, ,) (NN non-radioactive) (, ,) (CC and) (NN carbon-14)) (, ,) (NP (DT a) (JJ radioactive) (NN isotope)))))) (. .)))
All natural carbon occurs in three isotopes...carbon-12 and -13, non-radioactive, and carbon-14, a radioactive isotope.
(ROOT (S (NP (NP (NNP Carbon) (CD 14) (NN isotope)) (PP (IN of) (NP (NN carbon)))) (VP (VBZ is) (ADVP (RB typically)) (VP (VBN used) (PP (TO to) (NP (NN date) (JJ ancient) (NNS items))))) (. .)))