( ( Tracer ( A stable ) ) ( , ( easily ( ( detected ( ( ( substance or ) ( a radioisotope ) ) ( ( added ( to ( a material ) ) ) ( ( ( to ( follow ( ( the location ) ( of ( ( the substance ) ( in ( the environment ) ) ) ) ) ) ) or ) ( to ( detect ( ( any ( ( ( physical or ) chemical ) changes ) ) ( it undergoes ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN Tracer) (NP (DT A) (NN stable))) (, ,) (ADVP (RB easily)) (VP (VBD detected) (SBAR (S (NP (NP (NN substance)) (CC or) (NP (DT a) (NN radioisotope))) (VP (VBD added) (PP (TO to) (NP (DT a) (NN material))) (S (VP (VP (TO to) (VP (VB follow) (NP (NP (DT the) (NN location)) (PP (IN of) (NP (NP (DT the) (NN substance)) (PP (IN in) (NP (DT the) (NN environment)))))))) (CC or) (VP (TO to) (VP (VB detect) (NP (NP (DT any) (ADJP (NN physical) (CC or) (NN chemical)) (NNS changes)) (SBAR (S (NP (PRP it)) (VP (VBZ undergoes))))))))))))) (. .)))
Tracer A stable, easily detected substance or a radioisotope added to a material to follow the location of the substance in the environment or to detect any physical or chemical changes it undergoes.
(ROOT (S (NP (DT A) (NN tracer)) (VP (VBZ is) (NP (NP (DT the) (NN name)) (PP (IN for) (NP (NP (DT a) (NN substance)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (VP (VB be) (VP (VBN used) (S (VP (TO to) (VP (VB follow) (NP (NP (DT the) (NN pathway)) (PP (IN of) (NP (DT that) (NN substance)))) (PP (IN through) (NP (DT some) (NN structure))))))))))))))) (. .)))