( ( In fact ) ( , ( ( ( ( ( their function ) ( is circulatory ) ) and ) ( they ( are ( ( the ( fluid ( transport system ) ) ) ( of ( these leeches ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN In) (NP (NN fact))) (, ,) (S (NP (PRP$ their) (NN function)) (VP (VBZ is) (ADJP (JJ circulatory)))) (CC and) (S (NP (PRP they)) (VP (VBP are) (NP (NP (DT the) (JJ fluid) (NN transport) (NN system)) (PP (IN of) (NP (DT these) (NNS leeches)))))) (. .)))
In fact, their function is circulatory and they are the fluid transport system of these leeches.
(ROOT (S (NP (NP (DT The) (JJ main) (NN function)) (PP (IN of) (NP (DT the) (JJ circulatory) (NN system)))) (VP (VBZ is) (S (VP (TO to) (VP (VB transport) (NP (NNS materials)))))) (. .)))