He could be right boulders to be teaching then .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 He)) (VP_4 (MD_0 could) (VP_1 (ATVP_4 (VB_0 be) (NP_2 (JJ_1 right) (NNS_1 boulders))) (S_2 (VP_0 (TO_0 to) (VP_1 (VB_0 be) (VP_2 (VBG_0 teaching) (ADVP_0 (RB_0 then))))))))) (DOT_0 .)))