( ( Begin ( with ( one eye ) ) ) ( ( ( ( ( ( ( closed , ) and ) ( ( with ( your ( open ( eye stand ) ) ) ) ( in ( front ( of ( a mirror ) ) ) ) ) ) , ) and ) ( look ( at ( ( ( ( the pupil ) ( of ( your eye ) ) ) , ) ( close ( enough ( so ( that ( you ( ( see it ) ( in ( focus ( -LRB- ( ( not ( so ( easy ( for ( ( very high ) myopes ) ) ) ) ) -RRB- ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Begin)) (PP (IN with) (NP (CD one) (NN eye)))) (VP (VP (VBD closed)) (, ,) (CC and) (VP (PP (IN with) (NP (PRP$ your) (JJ open) (NN eye) (NN stand))) (PP (IN in) (NP (NP (NN front)) (PP (IN of) (NP (DT a) (NN mirror)))))) (, ,) (CC and) (VP (VBP look) (PP (IN at) (NP (NP (DT the) (NN pupil)) (PP (IN of) (NP (PRP$ your) (NN eye))) (, ,) (ADVP (RB close) (RB enough) (RB so) (SBAR (IN that) (S (NP (PRP you)) (VP (VBP see) (NP (PRP it)) (PP (IN in) (NP (NP (NN focus)) (PRN (-LRB- -LRB-) (FRAG (RB not) (ADJP (RB so) (JJ easy) (PP (IN for) (NP (ADJP (RB very) (JJ high)) (NNS myopes))))) (-RRB- -RRB-)))))))))))) (. .)))
Begin with one eye closed, and with your open eye stand in front of a mirror, and look at the pupil of your eye, close enough so that you see it in focus (not so easy for very high myopes).
(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))))))) (. .)))