(S (S (NP (BASENP (DT The) (NN march)) (PRN (COMMA ,) (VP (VBN held) (PP (IN in) (NP (BASENP (DT the) (NN center)) (PP (IN of) (BASENP (NNP Minsk)))))) (COMMA ,))) (VP (VBD marked) (NP (BASENP (DT the) (JJ 20th) (NN anniversary)) (PP (IN of) (BASENP (DT the) (NNP Chernobyl) (JJ nuclear) (NN disaster)))))) (PERIOD .))