( Plants ( ( ( provide us ) ( with ( ( oxygen and ) food ) ) ) . ) )
(ROOT (S (NP (NNS Plants)) (VP (VBP provide) (NP (PRP us)) (PP (IN with) (NP (NN oxygen) (CC and) (NN food)))) (. .)))
Plants provide us with oxygen and food.
(ROOT (S (NP (NNS Plants)) (VP (CONJP (RB not) (JJ only)) (VP (VBP contribute) (NP (NN food))) (CC but) (VP (VBD oxygen) (PP (IN for) (NP (NNS organisms))))) (. .)))