( ( Erosion ( of ( soil ( by water ) ) ) ) ( ( can ( take ( ( a variety ) ( of forms ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Erosion)) (PP (IN of) (NP (NP (NN soil)) (PP (IN by) (NP (NN water)))))) (VP (MD can) (VP (VB take) (NP (NP (DT a) (NN variety)) (PP (IN of) (NP (NNS forms)))))) (. .)))
Erosion of soil by water can take a variety of forms.
(ROOT (S (NP (NNP Soil)) (VP (VBZ is) (NP (NP (DT a) (JJ renewable) (NN resource)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (VP (VB take) (NP (NP (CD thousand)) (PP (IN of) (NP (NNS years)))) (S (VP (TO to) (VP (VB form)))))))))) (. .)))