beyond its limit to sustain a laugh 
(ROOT (S (PP (IN beyond) (NP (PRP$ its) (NN limit))) (S (VP (TO to) (VP (VB sustain) (NP (DT a) (NN laugh)))))))
(ROOT (S (PP (IN ) (NP (PRP$ ) (NN ))) (S (VP (TO ) (VP (VB ) (NP (DT ) (NN )))))))