(S (NP (BASENP (NN City) (NNS officials)) (PP (IN in) (BASENP (NN seven) (NNP United) (NNPS States) (NNS cities)))) (VP (VBD were) (VP (VP (VBN warned) (BASENP (NN today))) (PP (IN about) (NP (NP (BASENP (DT a) (JJ possible) (NN attack)) (PP (IN on) (BASENP (NNP NFL) (NNS stadiums)))) (VP (VBG using) (QT (DQL ``) (QTC (BASENP (JJ dirty) (NNS bombs)) (PERIOD .)) (DQR ''))))))))