( ( The sun ) ( ( is ( a ( star star ) ) ) , ) )
(ROOT (S (NP (DT The) (NN sun)) (VP (VBZ is) (NP (DT a) (NN star) (NN star))) (, ,)))
The sun is a star 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.