( ( A herbivore ) ( ( is ( ( a animal ) ( that ( only ( eats ( ( plants or ) grass ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN herbivore)) (VP (VBZ is) (NP (NP (DT a) (NN animal)) (SBAR (WHNP (WDT that)) (S (ADVP (RB only)) (VP (VBZ eats) (NP (NNS plants) (CC or) (NN grass))))))) (. .)))
A herbivore is a animal that only eats plants or grass.
(ROOT (S (NP (NNS Herbivores)) (VP (VBP are) (NP (NP (NNS heterotrophs)) (SBAR (WHNP (WDT that)) (S (VP (VBP eat) (NP (UCP (ADJP (JJ only)) (CC or) (ADVP (RB mainly))) (NNS plants))))))) (. .)))