the barriers finally prove to be too great 
(ROOT (S (NP (DT the) (NNS barriers)) (ADVP (RB finally)) (VP (VBP prove) (S (VP (TO to) (VP (VB be) (ADJP (RB too) (JJ great))))))))
(ROOT (S (NP (DT ) (NNS )) (ADVP (RB )) (VP (VBP ) (S (VP (TO ) (VP (VB ) (ADJP (RB ) (JJ ))))))))