( ( In fact ) ( , ( ( ( 78 % ) ( of ( ( the ( earth 's ) ) atmosphere ) ) ) ( ( is ( composed ( of ( nitrogen gas ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NN fact))) (, ,) (NP (NP (CD 78) (NN %)) (PP (IN of) (NP (NP (DT the) (NN earth) (POS 's)) (NN atmosphere)))) (VP (VBZ is) (VP (VBN composed) (PP (IN of) (NP (NN nitrogen) (NN gas))))) (. .)))
In fact, 78% of the earth's atmosphere is composed of nitrogen gas.
(ROOT (S (NP (NN Nitrogen) (NN gas)) (VP (VBZ comprises) (NP (NP (QP (RB about) (NNS three-fourths))) (PP (IN of) (NP (NP (NN earth) (POS 's)) (NN atmosphere))))) (. .)))