'I don't know what happened, exactly.' I said.
( ' ( ( ( ( ( I ( ( do n't ) ( know ( what ( ( happened , ) exactly ) ) ) ) ) . ) ' ) ( I said ) ) . ) )
(ROOT (S ('' ') (S (NP (PRP I)) (VP (VBP do) (RB n't) (VP (VB know) (SBAR (WHNP (WP what)) (S (VP (VBD happened) (, ,) (ADVP (RB exactly)))))))) (. .) ('' ') (S (NP (PRP I)) (VP (VBD said))) (. .)))
Something strange was going on.
( ( Something strange ) ( ( was ( going on ) ) . ) )
(ROOT (S (NP (NN Something) (JJ strange)) (VP (VBD was) (VP (VBG going) (PRT (RP on)))) (. .)))