I dropped going back Because the bag face-up muffled .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 I)) (VP_4 (VBD_1 dropped) (VP_2 (VBG_0 going) (ADVP_0 (RB_1 back) (PP_0 (IN_1 Because) (NP_4 (NP_5 (DT_0 the) (NN_2 bag)) (NP_6 (NN_3 face-up) (JJ_0 muffled)))))))) (DOT_0 .)))