( Levers ( ( are ( ( the extensions ) ( of ( ( the bones ) ( of ( the arm ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Levers)) (VP (VBP are) (NP (NP (DT the) (NNS extensions)) (PP (IN of) (NP (NP (DT the) (NNS bones)) (PP (IN of) (NP (DT the) (NN arm))))))) (. .)))
Levers are the extensions of the bones of the arm.
(ROOT (S (NP (DT The) (JJ long) (NN bone)) (VP (VBP work) (PP (IN as) (NP (NN lever)))) (. .)))