Err...I don't know.
( Err ( ... ( ( I ( ( do n't ) know ) ) . ) ) )
(ROOT (FRAG (NP (NNP Err)) (: ...) (S (NP (PRP I)) (VP (VBP do) (RB n't) (VP (VB know)))) (. .)))
I am not sure but I will find out.
( ( ( ( I ( ( am not ) sure ) ) but ) ( I ( will ( find out ) ) ) ) . )
(ROOT (S (S (NP (PRP I)) (VP (VBP am) (RB not) (ADJP (JJ sure)))) (CC but) (S (NP (PRP I)) (VP (MD will) (VP (VB find) (PRT (RP out))))) (. .)))