( ( The ( ( sympathetic nervous ) system ) ) ( ( plays ( ( a ( secondary role ) ) ( for ( the CBF ) ) ) ) . ) )
(ROOT (S (NP (DT The) (ADJP (JJ sympathetic) (JJ nervous)) (NN system)) (VP (VBZ plays) (NP (NP (DT a) (JJ secondary) (NN role)) (PP (IN for) (NP (DT the) (NNP CBF))))) (. .)))
The sympathetic nervous system plays a secondary role for the CBF.
(ROOT (S (NP (DT The) (JJ nervous) (NN system)) (VP (VBZ plays) (NP (NP (DT a) (JJ critical) (NN role)) (PP (IN in) (NP (NP (DT the) (NN regulation)) (PP (IN of) (NP (NN vascular) (NNS homeostasis))))))) (. .)))