stop buying tickets to these movies 
(ROOT (S (VP (VB stop) (S (VP (VBG buying) (NP (NP (NNS tickets)) (PP (IN to) (NP (DT these) (NNS movies)))))))))
(ROOT (S (VP (VB ) (S (VP (VBG ) (NP (NP (NNS )) (PP (IN ) (NP (DT ) (NNS )))))))))