that 's enough to sustain laughs 
(ROOT (S (NP (DT that)) (VP (VBZ 's) (ADJP (JJ enough) (S (VP (TO to) (VP (VB sustain) (NP (NNS laughs)))))))))
(ROOT (S (NP (DT )) (VP (VBZ ) (ADJP (JJ ) (S (VP (TO ) (VP (VB ) (NP (NNS )))))))))