( ( ( The ( Earth 's ) ) atmosphere ) ( ( ( is mostly ) ( ( made up ) ( of ( ( ( ( ( ( nitrogen gas ) ( -LRB- ( ( ( ( N 2 ) 78 ) % ) -RRB- ) ) ) , ) ( ( ( ( oxygen gas ) -LRB- ) ( O ( 2 ( 21 % ) ) ) ) , ) ) and ) ( other components ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN Earth) (POS 's)) (NN atmosphere)) (VP (VBZ is) (ADVP (RB mostly)) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (NP (NP (NN nitrogen) (NN gas)) (PRN (-LRB- -LRB-) (NP (QP ($ N) (CD 2) (CD 78)) (NN %)) (-RRB- -RRB-))) (, ,) (NP (NP (NN oxygen) (NN gas)) (-LRB- -LRB-) (NP (NP (NNP O)) (ADJP (CD 2) (CD 21) (NN %))) (, ,)) (CC and) (NP (JJ other) (NNS components)))))) (. .)))
The Earth's atmosphere is mostly made up of nitrogen gas (N 2 78%), oxygen gas (O 2 21%, and other components.
(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.