enough laughs to sustain interest to the end 
(ROOT (NP (NP (JJ enough) (NNS laughs)) (S (VP (TO to) (VP (VB sustain) (NP (NN interest)) (PP (IN to) (NP (DT the) (NN end))))))))
(ROOT (NP (NP (JJ ) (NNS )) (S (VP (TO ) (VP (VB ) (NP (NN )) (PP (IN ) (NP (DT ) (NN ))))))))