( ( ( The connection ) ( between ( pressure ( and ( fluid density ) ) ) ) ) ( ( is ( left out ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN connection)) (PP (IN between) (NP (NN pressure) (CC and) (NN fluid) (NN density)))) (VP (VBZ is) (VP (VBN left) (PRT (RP out)))) (. .)))
The connection between pressure and fluid density is left out.
(ROOT (S (NP (NNP Depth) (CC and) (NNP density)) (VP (VBP influence) (NP (NP (DT the) (NN pressure)) (PP (IN of) (NP (NNS fluids))))) (. .)))