bitten off more than he or anyone else could chew 
(ROOT (S (VP (VBN bitten) (PRT (RP off)) (NP (NP (RBR more)) (SBAR (IN than) (S (NP (NP (PRP he)) (CC or) (NP (NN anyone) (JJ else))) (VP (MD could) (VP (VB chew)))))))))
(ROOT (S (VP (VBN ) (PRT (RP )) (NP (NP (RBR )) (SBAR (IN ) (S (NP (NP (PRP )) (CC ) (NP (NN ) (JJ ))) (VP (MD ) (VP (VB )))))))))