to sustain a good simmer for most of its running time 
(ROOT (S (VP (TO to) (VP (VB sustain) (NP (DT a) (JJ good) (NN simmer)) (PP (IN for) (NP (NP (JJS most)) (PP (IN of) (NP (PRP$ its) (VBG running) (NN time)))))))))
(ROOT (S (VP (TO ) (VP (VB ) (NP (DT ) (JJ ) (NN )) (PP (IN ) (NP (NP (JJS )) (PP (IN ) (NP (PRP$ ) (VBG ) (NN )))))))))