alone , should scare any sane person away . 
(ROOT (S (ADVP (RB alone)) (, ,) (VP (MD should) (VP (VB scare) (NP (DT any) (JJ sane) (NN person)) (PRT (RB away)))) (. .)))
(ROOT (S (ADVP (RB )) (, ) (VP (MD ) (VP (VB ) (NP (DT ) (JJ ) (NN )) (PRT (RB )))) (. )))