it promised it would be 
(ROOT (S (NP (PRP it)) (VP (VBD promised) (SBAR (S (NP (PRP it)) (VP (MD would) (VP (VB be))))))))
(ROOT (S (NP (PRP )) (VP (VBD ) (SBAR (S (NP (PRP )) (VP (MD ) (VP (VB ))))))))