( ( Ocean waves ) ( ( are ( generated ( by ( ( the force ) ( of ( ( wind or ) tides ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Ocean) (NNS waves)) (VP (VBP are) (VP (VBN generated) (PP (IN by) (NP (NP (DT the) (NN force)) (PP (IN of) (NP (NN wind) (CC or) (NNS tides))))))) (. .)))
Ocean waves are generated by the force of wind or tides.
(ROOT (S (NP (NNP Ocean) (NNS waves)) (VP (VBP are) (ADVP (RB mainly)) (VP (VBN caused) (PP (IN by) (NP (NN wind))))) (. .)))