( ( ( except ( the concentration ) ) ( of urea ) ) ( ( stays high ) . ) )
(ROOT (S (NP (NP (IN except) (DT the) (NN concentration)) (PP (IN of) (NP (NN urea)))) (VP (VBZ stays) (ADJP (JJ high))) (. .)))
except the concentration of urea stays high.
(ROOT (S (NP (NNS Animals)) (VP (MD can) (VP (VP (VB transport) (NP (NP (DT the) (NN waste) (NN material)) (VP (VBN known) (PP (IN as) (NP (NP (NN urea)) (PP (IN in) (NP (DT the) (JJ circulatory) (NN system)))))))) (CC and) (VP (VB store) (NP (PRP it)) (ADVP (RB safely)) (PP (IN at) (NP (JJ high) (NNS concentrations)))))) (. .)))