( ( ( ( ( As ( ( a basis ) ( for ( understanding ( this concept ) ) ) ) ) ( , ( students know ) ) ) : ) ( ( most ( of ( most ( of ( the ( Earth ( s water ) ) ) ) ) ) ) ( ( is present ) ( as ( ( ( salt water ) ( in ( ( ( the oceans ) , ) ( which ( cover ( most ( of ( the earth ) ) ) ) ) ) ) ) ( s surface ) ) ) ) ) ) . )
(ROOT (S (S (PP (IN As) (NP (NP (DT a) (NN basis)) (PP (IN for) (S (VP (VBG understanding) (NP (DT this) (NN concept))))))) (, ,) (NP (NNS students)) (VP (VBP know))) (: :) (S (NP (NP (JJS most)) (PP (IN of) (NP (NP (JJS most)) (PP (IN of) (NP (DT the) (NNP Earth) (NNP s) (NN water)))))) (VP (VBZ is) (ADJP (JJ present)) (SBAR (IN as) (S (NP (NP (NN salt) (NN water)) (PP (IN in) (NP (NP (DT the) (NNS oceans)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBP cover) (NP (NP (JJS most)) (PP (IN of) (NP (DT the) (NN earth)))))))))) (VP (VBZ s) (NP (NN surface))))))) (. .)))
As a basis for understanding this concept, students know: most of most of the Earth s water is present as salt water in the oceans, which cover most of the earth s surface.
(ROOT (S (NP (NP (JJS Most)) (PP (IN of) (NP (NP (NN earth) (POS 's)) (NN water)))) (VP (VBZ is) (VP (VBN located) (PP (IN in) (NP (NNS oceans)))))))