(S (S (BASENP (DT The) (NNP Twin) (NNP Otter) (JJ propeller-driven) (NN aircraft)) (VP (VBZ has) (NP (NP (BASENP (DT a) (NN crew)) (PP (IN of) (BASENP (NN three)))) (CC and) (NP (BASENP (NN thirteen) (NNS passengers)) (COMMA ,) (SBAR (WHNP (BASENP (NN two)) (WHPP (IN of) (WHNP (WP whom)))) (S (VP (VBP are) (BASENP (NNS babies))))))))) (PERIOD .))