(S (S (BASENP (DT The) (NN flu)) (VP (VP (VBZ is) (ADJP (RB highly) (JJ contagious))) (CC but) (VP (VP (MD can) (RB not)) (VP (VB be) (VP (VBN transmitted) (PP (TO to) (BASENP (NNS humans)))))))) (PERIOD .))