( ( The ( mitral valve ) ) ( ( is ( one ( of ( ( the ( four valves ) ) ( of ( the heart ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ mitral) (NN valve)) (VP (VBZ is) (NP (NP (CD one)) (PP (IN of) (NP (NP (DT the) (CD four) (NNS valves)) (PP (IN of) (NP (DT the) (NN heart))))))) (. .)))
The mitral valve is one of the four valves of the heart.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD four) (NNS valves)) (PP (IN in) (NP (DT the) (NN heart))))) (. .)))