(S (S (BASENP (DT The) (NNP United) (NNPS States)) (VP (VP (VBZ has) (RB not)) (VP (VBN ratified) (NP (BASENP (DT the) (NNP Kyoto) (NNP Protocol)) (COMMA ,) (NP (BASENP (DT the) (NN 1997) (JJ international) (NN pact)) (SBAR (WHNP (WDT that)) (S (VP (VBZ requires) (NP (BASENP (NNS reductions)) (PP (IN in) (BASENP (NN greenhouse) (NN gas) (NNS emissions)))))))))))) (PERIOD .))