( ( ( return ( plasma proteins ) ) ( to ( the blood ) ) ) . )
(ROOT (S (VP (VB return) (NP (NN plasma) (NNS proteins)) (PP (TO to) (NP (DT the) (NN blood)))) (. .)))
return plasma proteins to the blood.
(ROOT (S (NP (DT The) (JJ complement) (NN system)) (VP (VBZ is) (NP (NP (DT a) (NN series)) (PP (IN of) (NP (NP (NNS proteins)) (VP (ADVP (RB constitutively)) (VBN found) (PP (IN in) (NP (DT the) (NN blood) (NN plasma)))))))) (. .)))