That sounds dangerous.
( That ( ( sounds dangerous ) . ) )
(ROOT (S (NP (DT That)) (VP (VBZ sounds) (ADJP (JJ dangerous))) (. .)))
That doesn't sound safe.
( That ( ( ( does n't ) ( sound safe ) ) . ) )
(ROOT (S (NP (DT That)) (VP (VBZ does) (RB n't) (VP (VB sound) (ADJP (JJ safe)))) (. .)))