( ( ( ( Nearly 99 ) percent ) ( of ( ( the ( earth 's ) ) atmosphere ) ) ) ( ( is ( ( nitrogen and ) oxygen ) ) . ) )
(ROOT (S (NP (NP (QP (RB Nearly) (CD 99)) (NN percent)) (PP (IN of) (NP (NP (DT the) (NN earth) (POS 's)) (NN atmosphere)))) (VP (VBZ is) (NP (NN nitrogen) (CC and) (NN oxygen))) (. .)))
Nearly 99 percent of the  earth's atmosphere is nitrogen and oxygen.
(ROOT (S (NP (NN Oxygen) (CC and) (NN nitrogen)) (VP (VBP make) (PRT (RP up)) (NP (NP (JJS most)) (PP (IN of) (NP (NP (DT the) (NN earth) (POS 's)) (NN atmosphere))))) (. .)))
Oxygen and nitrogen make up most of the earth's atmosphere.