(S (S (BASENP (PRP He)) (VP (VBD said) (SBAR (IN that) (S (NP (BASENP (NNS changes)) (PP (IN in) (NP (BASENP (NNP China)) (CC and) (BASENP (DT the) (NNP El) (NNP Niño))))) (VP (VBP remain) (PP (IN as) (NP (BASENP (DT the) (JJS biggest) (NNS challenges)) (PP (TO to) (BASENP (DT the) (NN economy)))))))))) (PERIOD .))