They mumbled in his friend unmistakably , <apostrophe><apostrophe> .
(ROOT_0 (S_0 (ATS_3 (ATS_0 (S_2 (NP_1 (PRP_0 They)) (VP_0 (ATVP_4 (VBD_2 mumbled) (PP_2 (IN_0 in) (NP_3 (PRPDOLLAR_0 his) (NN_0 friend)))) (ADVP_0 (RB_0 unmistakably)))) (COMMA_0 ,)) (APOSTROPHE_0 <apostrophe><apostrophe>)) (DOT_0 .)))