it 's good enough to be the purr 
(ROOT (S (NP (PRP it)) (VP (VBZ 's) (ADJP (JJ good) (RB enough) (S (VP (TO to) (VP (VB be) (NP (DT the) (NN purr)))))))))
(ROOT (S (NP (PRP )) (VP (VBZ ) (ADJP (JJ ) (RB ) (S (VP (TO ) (VP (VB ) (NP (DT ) (NN )))))))))