I have to tell you, I tried to understand it.
( ( I ( have ( to ( tell you ) ) ) ) ( , ( I ( ( tried ( to ( understand it ) ) ) . ) ) ) )
(ROOT (S (S (NP (PRP I)) (VP (VBP have) (S (VP (TO to) (VP (VB tell) (NP (PRP you))))))) (, ,) (NP (PRP I)) (VP (VBD tried) (S (VP (TO to) (VP (VB understand) (NP (PRP it)))))) (. .)))
I am upset that I can not understand it.
( I ( ( am ( upset ( that ( I ( ( can not ) ( understand it ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP I)) (VP (VBP am) (ADJP (VBN upset) (SBAR (IN that) (S (NP (PRP I)) (VP (MD can) (RB not) (VP (VB understand) (NP (PRP it)))))))) (. .)))