They used to be down a class teeth .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 They)) (VP_4 (VBD_2 used) (S_2 (VP_0 (TO_0 to) (VP_1 (ATVP_0 (VB_0 be) (PRT_0 (RP_0 down))) (NP_3 (ATNP_0 (DT_0 a) (NN_3 class)) (NNS_0 teeth))))))) (DOT_0 .)))