( ( ( The lack ) ( of ( water ( on ( ( the surface ) ( of ( ( Venus and ) Mars ) ) ) ) ) ) ) ( ( ( is then ) ( compared ( ( ( ( ( to ( ( the ( abundant water ) ) ( on Earth ) ) ) , ) and ) so ) on ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN lack)) (PP (IN of) (NP (NP (NN water)) (PP (IN on) (NP (NP (DT the) (NN surface)) (PP (IN of) (NP (NNP Venus) (CC and) (NNP Mars)))))))) (VP (VBZ is) (ADVP (RB then)) (VP (VBN compared) (PP (PP (TO to) (NP (NP (DT the) (JJ abundant) (NN water)) (PP (IN on) (NP (NNP Earth))))) (, ,) (CC and) (RB so) (PP (IN on))))) (. .)))
The lack of water on the surface of Venus and Mars is then compared to the abundant water on Earth, and so on.
(ROOT (S (NP (NP (DT The) (NN abundance)) (PP (IN of) (NP (NN water)))) (VP (VBZ makes) (NP (NP (DT the) (NN earth) (NN habitable)) (PP (IN for) (NP (NNS humans))))) (. .)))