The key question may be not what Hillary knew but when she knew it.
( ( The ( key question ) ) ( ( may ( ( be not ) ( ( ( what ( Hillary knew ) ) but ) ( when ( she ( knew it ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ key) (NN question)) (VP (MD may) (VP (VB be) (ADVP (RB not)) (SBAR (SBAR (WHNP (WP what)) (S (NP (NNP Hillary)) (VP (VBD knew)))) (CC but) (SBAR (WHADVP (WRB when)) (S (NP (PRP she)) (VP (VBD knew) (NP (PRP it)))))))) (. .)))
Hillary never knew anything.
( Hillary ( never ( ( knew anything ) . ) ) )
(ROOT (S (NP (NNP Hillary)) (ADVP (RB never)) (VP (VBD knew) (NP (NN anything))) (. .)))