( ( Radioisotope ( ( A ( radioactive isotope ) ) ( of ( an element ) ) ) ) . )
(ROOT (S (VP (VB Radioisotope) (NP (NP (DT A) (JJ radioactive) (NN isotope)) (PP (IN of) (NP (DT an) (NN element))))) (. .)))
Radioisotope A radioactive isotope of an element.
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NNS radioisotopes)) (VP (VBZ is) (NP (NP (DT an) (NN isotope)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (ADJP (JJ radioactive))))))) (. .)))