( Toxicity ( ( was ( demonstrated ( to ( be ( of ( a ( ( very low ) order ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Toxicity)) (VP (VBD was) (VP (VBN demonstrated) (S (VP (TO to) (VP (VB be) (PP (IN of) (NP (DT a) (ADJP (RB very) (JJ low)) (NN order)))))))) (. .)))
Toxicity was demonstrated to be of a very low order.
(ROOT (S (NP (NP (DT The) (JJ main) (NN advantage)) (PP (IN of) (NP (NN urea)))) (VP (VBZ is) (NP (PRP$ its) (ADJP (RB very) (JJ low)) (NN toxicity))) (. .)))