them knew This , <apostrophe>s on the gravel .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 them)) (VP_4 (VBD_0 knew) (NP_3 (NP_4 (ATNP_0 (NP_0 (DT_1 This)) (COMMA_0 ,)) (POS_0 <apostrophe>s)) (PP_0 (IN_1 on) (NP_5 (DT_0 the) (NN_2 gravel)))))) (DOT_0 .)))