( Saturn ( ( orbits ( ( ( the Sun ) once ) ( every ( 29.4 ( Earth years ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Saturn)) (VP (VBZ orbits) (S (NP (DT the) (NNP Sun)) (ADVP (RB once)) (NP (DT every) (CD 29.4) (NNP Earth) (NNS years)))) (. .)))
Saturn orbits the Sun once every 29.4 Earth years.
(ROOT (S (NP (NNP Earth)) (VP (VBZ makes) (NP (DT a) (JJ complete) (NN revolution)) (NP (ADVP (IN around) (NP (DT the) (NN sun)) (PP (IN about) (ADVP (RB once)))) (DT every) (NN year))) (. .)))