it 's hard to stop watching 
(ROOT (S (NP (NP (PRP it))) (VP (VBZ 's) (ADJP (JJ hard)) (S (VP (TO to) (VP (VB stop) (S (VP (VBG watching)))))))))
(ROOT (S (NP (NP (PRP ))) (VP (VBZ ) (ADJP (JJ )) (S (VP (TO ) (VP (VB ) (S (VP (VBG )))))))))