( ( If ( we ( multiply ( ( the amount ) ( of ( power ( used ( by ( ( the length ) ( of time ) ) ) ) ) ) ) ) ) ) ( it ( ( is ( used ( we ( obtain ( ( ( the amount ) ( of energy ) ) ( ( the house ) ( has consumed ) ) ) ) ) ) ) . ) ) )
(ROOT (S (SBAR (IN If) (S (NP (PRP we)) (VP (VB multiply) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN power)) (VP (VBN used) (PP (IN by) (NP (NP (DT the) (NN length)) (PP (IN of) (NP (NN time)))))))))))) (NP (PRP it)) (VP (VBZ is) (VP (VBN used) (S (NP (PRP we)) (VP (VB obtain) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN energy))) (SBAR (S (NP (DT the) (NN house)) (VP (VBZ has) (VP (VBN consumed)))))))))) (. .)))
If we multiply the amount of power used by the length of time it is used we obtain the amount of energy the house has consumed.
(ROOT (S (NP (NP (JJ Electrical) (NN energy)) (VP (VBN consumed))) (VP (MD can) (VP (VB be) (VP (VBN expressed) (PP (IN as) (NP (NP (DT the) (NN product)) (PP (IN of) (NP (NP (NN power)) (VP (VBN multiplied) (PP (IN by) (NP (NN time))))))))))) (. .)))