( ( The WIND ) ( ( causes waves ) . ) )
(ROOT (S (NP (DT The) (NNP WIND)) (VP (VBZ causes) (NP (NNS waves))) (. .)))
The WIND causes waves.
(ROOT (S (NP (NNP Ocean) (NNS waves)) (VP (VBP are) (ADVP (RB mainly)) (VP (VBN caused) (PP (IN by) (NP (NN wind))))) (. .)))