They could be off for the class just .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 They)) (VP_4 (MD_0 could) (VP_1 (ATVP_2 (ATVP_0 (VB_0 be) (PRT_0 (RP_0 off))) (PP_0 (IN_1 for) (NP_5 (DT_0 the) (NN_2 class)))) (ADVP_0 (RB_0 just))))) (DOT_0 .)))