'Why isn't a lookalike good enough for them?'
( ` ( Why ( ( ( ( is n't ) ( ( a ( lookalike ( good enough ) ) ) ( for them ) ) ) ? ) ' ) ) )
(ROOT (SBARQ (`` `) (WHADVP (WRB Why)) (SQ (VBZ is) (ADVP (RB n't)) (NP (NP (DT a) (JJ lookalike) (JJ good) (NN enough)) (PP (IN for) (NP (PRP them))))) (. ?) ('' ')))
How come the look alike isn't good enough to be a stunt double? 
( How ( ( ( come ( ( the look ) ( alike ( ( is n't ) ( ( good enough ) ( to ( be ( a stunt ) ) ) ) ) ) ) ) double ) ? ) )
(ROOT (SBARQ (WHADVP (WRB How)) (SINV (VP (VBP come) (SBAR (S (NP (DT the) (NN look)) (ADVP (RB alike)) (VP (VBZ is) (RB n't) (ADJP (JJ good) (RB enough) (S (VP (TO to) (VP (VB be) (NP (DT a) (NN stunt)))))))))) (NP (VB double))) (. ?)))