i'm not exactly sure
( i ( ( 'm not ) ( exactly sure ) ) )
(ROOT (S (NP (FW i)) (VP (VBP 'm) (RB not) (ADJP (RB exactly) (JJ sure)))))
I'm not sure.
( I ( ( ( 'm not ) sure ) . ) )
(ROOT (S (NP (PRP I)) (VP (VBP 'm) (RB not) (ADJP (JJ sure))) (. .)))