( ( Their ( main advantages ) ) ( ( are ( ( low ( ( toxicity and ) ease ) ) ( of disposal ) ) ) . ) )
(ROOT (S (NP (PRP$ Their) (JJ main) (NNS advantages)) (VP (VBP are) (NP (NP (JJ low) (NN toxicity) (CC and) (NN ease)) (PP (IN of) (NP (NN disposal))))) (. .)))
Their main advantages are low toxicity and ease of disposal.
(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))) (. .)))