(S (S (PP (IN In) (BASENP (PRPD their) (NN response))) (COMMA ,) (S (BASENP (NNP Nature)) (VP (VP (VP (VBD refused) (S (VP (TO to) (VP (VP (VB reveal) (BASENP (PRPD their) (JJ original) (NN data))) (PP (IN for) (BASENP (NN comparison))))))) (CONJP (COMMA ,) (CC and)) (VP (VBD commented) (SBAR (IN that) (S (BASENP (NNP Britannica)) (VP (VBD had) (VP (VP (VP (VBN raised) (BASENP (PRPD their) (NNS grievances))) (PP (IN in) (BASENP (NN private)))) (ADVP (BASENP (DT some) (NN time)) (RB ago)))))))) (CONJP (COMMA ,) (CC and)) (VP (VP (ADVP (RB then)) (VP (VBD received) (BASENP (DT no) (JJ further) (NN correspondence)))) (SBAR (IN until) (S (BASENP (NNP Britannicas)) (VP (VBD open) (NP (BASENP (NN letter)) (PP (IN of) (BASENP (NN 22) (NNP March) (NN 2006))))))))))) (PERIOD .))