( ( ( The motion ) ( of ( the system ) ) ) ( ( can ( be ( characterized simply ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN motion)) (PP (IN of) (NP (DT the) (NN system)))) (VP (MD can) (VP (VB be) (VP (VBN characterized) (ADVP (RB simply))))) (. .)))
The motion of the system can be characterized simply.
(ROOT (S (NP (NNP Motion)) (VP (MD can) (VP (VB be) (VP (VBN defined) (ADVP (RB simply)) (PP (IN as) (NP (NP (DT a) (NN change)) (PP (IN in) (NP (NN position)))))))) (. .)))