i last walked out on a movie 
(ROOT (S (NP (PRP i)) (ADVP (RB last)) (VP (VBD walked) (PRT (RP out)) (PP (IN on) (NP (DT a) (NN movie))))))
(ROOT (S (NP (PRP )) (ADVP (RB )) (VP (VBD ) (PRT (RP )) (PP (IN ) (NP (DT ) (NN ))))))