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(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 He)) (VP_4 (MD_0 <apostrophe>ll) (VP_1 (ATVP_0 (VB_0 keep) (PRT_0 (RP_0 on))) (SBAR_0 (WHADVP_0 (WRB_0 when)) (S_1 (NP_0 (PRP_1 I)) (VP_5 (VBD_1 was) (NP_3 (PRPDOLLAR_0 His) (NN_0 air)))))))) (DOT_0 .)))