who it narrowed , they knew .
(ROOT_0 (S_0 (ATS_3 (ATS_1 (ATS_2 (SBAR_0 (WHNP_0 (WP_0 who)) (S_1 (NP_0 (PRP_1 it)) (VP_5 (VBD_1 narrowed)))) (COMMA_0 ,)) (NP_0 (PRP_1 they))) (VP_3 (VBD_0 knew))) (DOT_0 .)))