( ( The sun ) ( ( is ( a star ) ) . ) )
(ROOT (S (NP (DT The) (NN sun)) (VP (VBZ is) (NP (DT a) (NN star))) (. .)))
The sun is a star.
(ROOT (S (NP (DT The) (NN sun)) (VP (VBZ is) (VP (VBN classified) (PP (IN as) (NP (DT a) (NN star))))) (. .)))
The sun is classified as a star.