( ( ( The ( four valves ) ) ( of ( the heart ) ) ) ( ( ( are ( the gateways ) ) ( through ( the chambers ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (CD four) (NNS valves)) (PP (IN of) (NP (DT the) (NN heart)))) (VP (VBP are) (NP (DT the) (NNS gateways)) (PP (IN through) (NP (DT the) (NNS chambers)))) (. .)))
The four valves of the heart are the gateways through the chambers.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD four) (NNS valves)) (PP (IN in) (NP (DT the) (NN heart))))) (. .)))