(S (S (SBAR (IN Although) (S (S (BASENP (RB only) (NN two)) (VP (VBP are) (VP (VBN required) (PP (IN for) (BASENP (JJ normal) (NN operation)))))) (CONJP (COMMA ,) (CC and)) (S (BASENP (DT the) (NNP Shuttle)) (VP (MD can) (VP (VB be) (VP (VBN flown) (PP (IN with) (BASENP (NN one))))))))) (COMMA ,) (S (BASENP (NNP NASA)) (VP (VBD elected) (S (VP (TO to) (VP (VB maintain) (BASENP (JJ full) (NN redundancy)))))))) (PERIOD .))