Never know where they won't turn up next. 
( Never ( ( know ( where ( they ( ( wo n't ) ( turn ( up next ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Never)) (VP (VBP know) (SBAR (WHADVP (WRB where)) (S (NP (PRP they)) (VP (MD wo) (RB n't) (VP (VB turn) (ADVP (RB up) (JJ next))))))) (. .)))
Who knows where they will turn up next.
( Who ( ( knows ( where ( they ( will ( turn ( up next ) ) ) ) ) ) . ) )
(ROOT (SBARQ (WHNP (WP Who)) (SQ (VP (VBZ knows) (SBAR (WHADVP (WRB where)) (S (NP (PRP they)) (VP (MD will) (VP (VB turn) (ADVP (RB up) (JJ next)))))))) (. .)))