may be based on a true and historically significant story 
(ROOT (VP (MD may) (VP (VB be) (VP (VBN based) (PP (IN on) (NP (DT a) (ADJP (ADJP (JJ true)) (CC and) (ADJP (RB historically) (JJ significant))) (NN story)))))))
(ROOT (VP (MD ) (VP (VB ) (VP (VBN ) (PP (IN ) (NP (DT ) (ADJP (ADJP (JJ )) (CC ) (ADJP (RB ) (JJ ))) (NN )))))))