( Day ( ( A day ) ( ( is ( ( the time ) ( ( taken ( for ( the earth ) ) ) ( to ( ( rotate once ) ( on ( its axis ) ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (NNP Day)) (NP (DT A) (NN day)) (VP (VBZ is) (NP (NP (DT the) (NN time)) (VP (VBN taken) (PP (IN for) (NP (DT the) (NN earth))) (S (VP (TO to) (VP (VB rotate) (ADVP (RB once)) (PP (IN on) (NP (PRP$ its) (NNS axis))))))))) (. .)))
Day A day is the time taken for the earth to rotate once on its axis .
(ROOT (S (NP (NNP Earth)) (VP (VBZ rotates) (PP (PP (IN on) (NP (PRP$ its) (NNS axis)) (ADVP (RB once))) (CC times) (PP (IN in) (NP (CD one) (NN day))))) (. .)))