( ( According ( to Chapman ) ) ( , ( ( water ( from ( ( ancient rivers ) ( flowing ( across ( the ( Red Planet ) ) ) ) ) ) ) ( ( ( may still ) ( ( exist ( in ( ( the form ) ( of ice ) ) ) ) ( beneath ( ( rock-covered basins ) ( near ( ( the equator ) ( of Mars ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (VBG According) (PP (TO to) (NP (NNP Chapman)))) (, ,) (NP (NP (NN water)) (PP (IN from) (NP (NP (JJ ancient) (NNS rivers)) (VP (VBG flowing) (PP (IN across) (NP (DT the) (NNP Red) (NN Planet))))))) (VP (MD may) (ADVP (RB still)) (VP (VB exist) (PP (IN in) (NP (NP (DT the) (NN form)) (PP (IN of) (NP (NN ice))))) (PP (IN beneath) (NP (NP (JJ rock-covered) (NNS basins)) (PP (IN near) (NP (NP (DT the) (NN equator)) (PP (IN of) (NP (NNP Mars))))))))) (. .)))
According to Chapman, water from ancient rivers flowing across the Red Planet may still exist in the form of ice beneath rock-covered basins near the equator of Mars.
(ROOT (S (NP (NNP Water)) (VP (VBZ takes) (NP (NP (DT the) (NN form)) (PP (IN of) (NP (NN ice)))) (PP (IN on) (NP (NN planet) (NNS mars)))) (. .)))