( ( ( ( ( ( ( The maximum ) ( ( ( the ( eye 's ) ) pupil ) ( can open ) ) ) ( is ( ( about 7 ) millimeters ) ) ) , ) but ) ( it ( diminishes ( with age ) ) ) ) . )
(ROOT (S (S (NP (NP (DT The) (NN maximum)) (SBAR (S (NP (NP (DT the) (NN eye) (POS 's)) (NN pupil)) (VP (MD can) (VP (VB open)))))) (VP (VBZ is) (NP (QP (RB about) (CD 7)) (NNS millimeters)))) (, ,) (CC but) (S (NP (PRP it)) (VP (VBZ diminishes) (PP (IN with) (NP (NN age))))) (. .)))
The maximum the eye's pupil can open is about 7 millimeters, but it diminishes with age.
(ROOT (S (NP (DT The) (NN pupil)) (VP (VBZ is) (NP (NP (DT the) (NN opening)) (PP (IN in) (NP (NP (DT the) (NN front)) (PP (IN of) (NP (DT the) (NN eye))))))) (. .)))