(S (S (PP (IN During) (BASENP (DT the) (NNS 1980s))) (COMMA ,) (S (SBAR (IN while) (FRAG (ADJP (RB still)) (NP (BASENP (DT a) (NN prisoner)) (PP (IN on) (BASENP (NNP Robben) (NNP Island)))))) (COMMA ,) (S (BASENP (PRP he)) (VP (VBD developed))))) (PERIOD .))