(S (S (PP (IN Unlike) (BASENP (JJ previous) (DT such) (NNS explosions))) (COMMA ,) (S (BASENP (DT this) (NN explosion)) (VP (VP (VBD did) (RB not)) (VP (VB appear) (S (VP (TO to) (VP (VB be) (VP (VBN set) (PP (IN by) (BASENP (DT a) (NN suicide) (NN bomber))))))))))) (PERIOD .))