( Rain ( ( is ( ( the precipitation ) ( of ( ( liquid drops ) ( of water ) ) ) ) ) . ) )
(ROOT (S (NP (NN Rain)) (VP (VBZ is) (NP (NP (DT the) (NN precipitation)) (PP (IN of) (NP (NP (JJ liquid) (NNS drops)) (PP (IN of) (NP (NN water))))))) (. .)))
Rain is the precipitation of liquid drops of water.
(ROOT (S (NP (NN Rain)) (VP (VBZ is) (NP (NP (DT an) (NN example)) (PP (IN of) (NP (JJ liquid) (NN water))))) (. .)))