( ( Our atmosphere ) ( ( contains ( ( ( ( ( ( ( ( ( 21 % ) oxygen ) , ) ( which ( ( is ( necessary ( for us ) ) ) ( to breathe ) ) ) ) , ) ( ( 78 % ) nitrogen ) ) , ) and ) ( ( .9 % ) argon ) ) ) . ) )
(ROOT (S (NP (PRP$ Our) (NN atmosphere)) (VP (VBZ contains) (NP (NP (NP (ADJP (CD 21) (NN %)) (NN oxygen)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADJP (JJ necessary) (PP (IN for) (NP (PRP us)))) (S (VP (TO to) (VP (VB breathe)))))))) (, ,) (NP (ADJP (CD 78) (NN %)) (NN nitrogen)) (, ,) (CC and) (NP (NP (CD .9) (NN %)) (NP (NNP argon))))) (. .)))
Our atmosphere contains 21% oxygen, which is necessary for us to breathe, 78% nitrogen, and .9% argon.
(ROOT (S (NP (NNP Nitrogen) (, ,) (NNP oxygen) (CC and) (NNP argon)) (VP (VBP are) (NP (NP (DT the) (CD three) (JJS most) (JJ common) (NNS elements)) (PP (IN in) (NP (NP (DT the) (NN air)) (SBAR (S (NP (PRP we)) (VP (VB breathe)))))))) (. .)))