(S (S (BASENP (DT The) (NN three) (JJ armed) (NNS robbers)) (VP (VP (VBD entered) (BASENP (DT the) (NN museum))) (PP (BASENP (PDT half) (DT an) (NN hour)) (PP (IN before) (BASENP (NN closing)))))) (PERIOD .))