But fortunately they didn't.
( But ( fortunately ( they ( ( did n't ) . ) ) ) )
(ROOT (S (CC But) (ADVP (RB fortunately)) (NP (PRP they)) (VP (VBD did) (RB n't)) (. .)))
I know they were going to, and I knew they already did it. 
( ( ( ( ( I ( know ( they ( were ( going to ) ) ) ) ) , ) and ) ( I ( knew ( they ( already ( did it ) ) ) ) ) ) . )
(ROOT (S (S (NP (PRP I)) (VP (VBP know) (SBAR (S (NP (PRP they)) (VP (VBD were) (VP (VBG going) (PP (TO to)))))))) (, ,) (CC and) (S (NP (PRP I)) (VP (VBD knew) (SBAR (S (NP (PRP they)) (ADVP (RB already)) (VP (VBD did) (NP (PRP it))))))) (. .)))