(S (S (PP (IN Without) (NP (BASENP (DT the) (NN recovery)) (PP (IN of) (BASENP (DT the) (NNS recorders))))) (COMMA ,) (S (BASENP (NNS investigators)) (VP (MD may) (VP (VB be) (ADJP (JJ unable) (S (VP (TO to) (VP (VB determine) (NP (BASENP (DT the) (NN cause)) (PP (IN of) (BASENP (DT the) (NN crash)))))))))))) (PERIOD .))