( ( For ( ( example , ) ( the isotope ) ) ) ( , ( ( carbon 14 ) ( ( decays ( to ( ( carbon 12 ) ( at ( a ( known rate ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (NP (NN example)) (, ,) (NP (DT the) (NN isotope)))) (, ,) (NP (NN carbon) (CD 14)) (VP (VBZ decays) (PP (TO to) (NP (NP (NN carbon) (CD 12)) (PP (IN at) (NP (DT a) (VBN known) (NN rate)))))) (. .)))
For example, the isotope, carbon 14 decays to carbon 12 at a known rate.
(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))))) (. .)))