( ( For ( years now ) ) ( , ( scientists ( ( have ( ( used ( the ( radioactive ( element Carbon-14 ) ) ) ) ( as ( ( a ( major method ) ) ( in ( ( dating ( ( ( items , ) ( such ( as ( ( ( ( ( fossils , ) ( ( ash ( , primitive ) ) ( ( tools and ) dishes ) ) ) , ) and ) ( ancient artifacts ) ) ) ) ) , ) ) ( among others ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (NP (NNS years)) (ADVP (RB now)))) (, ,) (NP (NNS scientists)) (VP (VBP have) (VP (VBN used) (NP (DT the) (JJ radioactive) (NN element) (NN Carbon-14)) (PP (IN as) (NP (NP (DT a) (JJ major) (NN method)) (PP (IN in) (S (VP (VBG dating) (NP (NP (NNS items)) (, ,) (PP (JJ such) (IN as) (NP (NP (NNS fossils)) (, ,) (NP (ADJP (JJ ash) (, ,) (JJ primitive)) (NNS tools) (CC and) (NNS dishes)) (, ,) (CC and) (NP (JJ ancient) (NNS artifacts)))) (, ,)) (PP (IN among) (NP (NNS others)))))))))) (. .)))
For years now, scientists have used the radioactive element Carbon-14 as a major method in dating items, such as fossils, ash, primitive tools and dishes, and ancient artifacts, among others.
(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))))) (. .)))