(S (S (NP (BASENP (NN Opinion) (NNS polls)) (SBAR (SBAR (S (VP (VBN held)))) (SBAR (IN before) (S (BASENP (DT the) (NNS polls)) (VP (VBD closed)))))) (VP (VBD showed) (S (BASENP (NNP Obama)) (VP (VBG winning))))) (PERIOD .))