( Plants ( ( provide ( ( ( ( oxygen , ) ( a gas ) ) , ) ( that ( ( most ( living things ) ) ( need ( ( in order ) ( to live ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Plants)) (VP (VBP provide) (NP (NP (NN oxygen)) (, ,) (NP (DT a) (NN gas)) (, ,) (SBAR (IN that) (S (NP (JJS most) (NN living) (NNS things)) (VP (VBP need) (SBAR (IN in) (NN order) (S (VP (TO to) (VP (VB live)))))))))) (. .)))
Plants provide oxygen, a gas, that most living things need in order to live.
(ROOT (S (NP (NN Oxygen) (NN gas)) (VP (VBZ is) (VP (VBN given) (PRT (RP off)) (PP (IN by) (NP (NNS plants))))) (. .)))