it might have held my attention , but 
(ROOT (S (S (NP (PRP it)) (VP (MD might) (VP (VB have) (VP (VBN held) (NP (PRP$ my) (NN attention)))))) (, ,) (CC but)))
(ROOT (S (S (NP (PRP )) (VP (MD ) (VP (VB ) (VP (VBN ) (NP (PRP$ ) (NN )))))) (, ) (CC )))