( ( ( ( Look ( at ( the ( solar system ) ) ) ) -- ) ( ( the sun ) ( is ( in ( the center ) ) ) ) ) . )
(ROOT (S (S (VP (VB Look) (PP (IN at) (NP (DT the) (JJ solar) (NN system))))) (: --) (S (NP (DT the) (NN sun)) (VP (VBZ is) (PP (IN in) (NP (DT the) (NN center))))) (. .)))
Look at the solar system -- the sun is in the center.
(ROOT (S (NP (DT The) (NN sun)) (VP (VBZ is) (VP (VBN considered) (NP (NP (DT the) (NN center)) (PP (IN of) (NP (DT the) (JJ solar) (NN system)))))) (. .)))