(S (S (NP (BASENP (DT A) (JJ significant) (NN number)) (PP (IN of) (BASENP (DT the) (VBN affected) (NNS houses)))) (VP (VBD had) (VP (VBN been) (VP (VBN built) (PP (IN of) (BASENP (NN mud))))))) (PERIOD .))