( ( When ( people breathe ) ) ( , ( it ( ( ( is ( the oxygen ) ) ( that ( we ( ( take out ) ( of ( the ( air ( to ( ( keep ( our ( ( cells and ) bodies ) ) ) alive ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NNS people)) (VP (VB breathe)))) (, ,) (NP (PRP it)) (VP (VBZ is) (NP (DT the) (NN oxygen)) (SBAR (IN that) (S (NP (PRP we)) (VP (VBP take) (PRT (RP out)) (PP (IN of) (NP (DT the) (NN air) (S (VP (TO to) (VP (VB keep) (NP (PRP$ our) (NNS cells) (CC and) (NNS bodies)) (ADVP (RB alive))))))))))) (. .)))
When people breathe, it is the oxygen that we take out of the air to keep our cells and bodies alive.
(ROOT (S (NP (DT An) (JJ underwater) (NN spider)) (VP (VBZ uses) (NP (JJ shiny) (NN air) (NN bubble) (S (VP (TO to) (VP (VP (VB breathe)) (CC and) (VP (VB keep) (ADJP (JJ alive)))))))) (. .)))