(S (S (BASENP (DT A) (JJ Russian) (NN teenager)) (VP (VBZ has) (VP (VBN accomplished) (NP (BASENP (DT an) (JJ unprecedented) (NN feat)) (PP (IN in) (NP (BASENP (DT the) (NN history)) (PP (IN of) (BASENP (NN world) (NN aviation))))))))) (PERIOD .))