\\ They wasn't ghosts.
( \ ( ( \ ( They ( ( was n't ) ghosts ) ) ) . ) )
(ROOT (S (NP (NNP \)) (VP (VBD \) (SBAR (S (NP (PRP They)) (VP (VBD was) (RB n't) (NP (NNS ghosts)))))) (. .)))
They were ghosts. 
( They ( ( were ghosts ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD were) (NP (NNS ghosts))) (. .)))