( Answer ( : ( ( ( A ( neutron star ) ) ( is ( ( a ( dense ball ) ) ( of ( neutrons ( that ( ( remains ( at ( ( the core ) ( of ( a star ) ) ) ) ) ( after ( ( a ( supernova explosion ) ) ( has ( destroyed ( ( the rest ) ( of ( the star ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (FRAG (NP (NNP Answer)) (: :) (S (NP (DT A) (NN neutron) (NN star)) (VP (VBZ is) (NP (NP (DT a) (JJ dense) (NN ball)) (PP (IN of) (NP (NP (NNS neutrons)) (SBAR (WHNP (WDT that)) (S (VP (VBZ remains) (PP (IN at) (NP (NP (DT the) (NN core)) (PP (IN of) (NP (DT a) (NN star))))) (SBAR (IN after) (S (NP (DT a) (NN supernova) (NN explosion)) (VP (VBZ has) (VP (VBN destroyed) (NP (NP (DT the) (NN rest)) (PP (IN of) (NP (DT the) (NN star)))))))))))))))) (. .)))
Answer : A neutron star is a dense ball of neutrons that remains at the core of a star after a supernova explosion has destroyed the rest of the star.
(ROOT (S (NP (NN Neutron) (NNS stars)) (VP (VBP are) (NP (NP (DT the) (NNS corpses)) (PP (IN of) (NP (ADJP (VBN left) (RP over)) (NN supernova) (NNS explosions))))) (. .)))