He watched them doing up alpaca .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 He)) (VP_4 (VBD_2 watched) (S_2 (NP_1 (PRP_0 them)) (VP_0 (ATVP_0 (VBG_0 doing) (PRT_0 (RP_0 up))) (NP_2 (NN_3 alpaca)))))) (DOT_0 .)))