oh i'll bet they did
( ( oh i ) ( 'll ( bet ( they did ) ) ) )
(ROOT (S (NP (NNP oh) (NNP i)) (VP (MD 'll) (VP (VB bet) (SBAR (S (NP (PRP they)) (VP (VBD did))))))))
I'm sure they did
( I ( 'm ( sure ( they did ) ) ) )
(ROOT (S (NP (PRP I)) (VP (VBP 'm) (ADJP (JJ sure) (SBAR (S (NP (PRP they)) (VP (VBD did))))))))