fighting off the urge to doze 
(ROOT (S (VP (VBG fighting) (PRT (RP off)) (NP (DT the) (NN urge) (S (VP (TO to) (VP (VB doze))))))))
(ROOT (S (VP (VBG ) (PRT (RP )) (NP (DT ) (NN ) (S (VP (TO ) (VP (VB ))))))))