(S (S (NP (BASENP (NNS Reports)) (PP (IN from) (NP (BASENP (NNP MSNBC)) (CC and) (BASENP (DT the) (NNP Guardian) (NNP Unlimited))))) (VP (VBP say) (SBAR (IN that) (S (S (BASENP (DT the) (NN shaft)) (VP (MD may) (VP (VB have) (VP (VBN collapsed))))) (SBAR (WHADVP (WRB when)) (S (BASENP (DT a) (NN water) (CC or) (NN air) (NN pipe)) (VP (VBD burst)))))))) (PERIOD .))