( ( The Earth ) ( ( ( rotates ( on ( its axis ) ) ) ( once ( each day ) ) ) . ) )
(ROOT (S (NP (DT The) (NN Earth)) (VP (VBZ rotates) (PP (IN on) (NP (PRP$ its) (NNS axis))) (NP (RB once) (DT each) (NN day))) (. .)))
The Earth rotates on its axis once each day.
(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))))) (. .)))