( ( ( The speed ) ( of ( a wave ) ) ) ( ( is ( ( the wavelength ) ( times ( the frequency ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN speed)) (PP (IN of) (NP (DT a) (NN wave)))) (VP (VBZ is) (NP (NP (DT the) (NN wavelength)) (PP (CC times) (NP (DT the) (NN frequency))))) (. .)))
The speed of a wave is the wavelength times the frequency.
(ROOT (S (NP (NP (DT The) (NN product)) (PP (IN of) (NP (NP (NP (DT a) (NN wave) (POS 's)) (NN wavelength)) (CC and) (NP (PRP$ its) (NN frequency))))) (VP (VBZ is) (NP (PRP$ its) (NN speed))) (. .)))