It should be teaching At with hat of someone and had .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 It)) (VP_4 (ATVP_1 (VP_5 (MD_0 should) (VP_1 (VB_0 be) (S_2 (VP_0 (VBG_0 teaching) (PP_2 (IN_0 At) (PP_2 (IN_0 with) (NP_3 (NP_5 (NN_3 hat)) (PP_0 (IN_1 of) (NP_2 (NN_3 someone)))))))))) (CC_0 and)) (VP_5 (VBD_1 had)))) (DOT_0 .)))