(S (S (NP (BASENP (NNP Gou)) (PRN (COMMA ,) (VP (VBG bowing) (PP (IN as) (NP (BASENP (DT an) (NN expression)) (PP (IN of) (BASENP (NN regret)))))) (COMMA ,))) (VP (VBD promised) (S (VP (TO to) (VP (VB work) (S (VP (TO to) (VP (VB prevent) (S (BASENP (JJ such) (NNS tragedies)) (VP (VBN occurring) (ADVP (RB again)))))))))))) (PERIOD .))