i 'm sure mainstream audiences will be baffled , 
(ROOT (S (NP (PRP i)) (VP (VBP 'm) (ADJP (JJ sure) (SBAR (S (NP (JJ mainstream) (NNS audiences)) (VP (MD will) (VP (VB be) (ADJP (VBN baffled)))))))) (, ,)))
(ROOT (S (NP (PRP )) (VP (VBP ) (ADJP (JJ ) (SBAR (S (NP (JJ ) (NNS )) (VP (MD ) (VP (VB ) (ADJP (VBN )))))))) (, )))