( ( ( Calculate ( the percent ) ) ( by ( mass ( of ( each element ) ) ) ) ) . )
(ROOT (S (VP (VB Calculate) (NP (DT the) (NN percent)) (PP (IN by) (NP (NP (NN mass)) (PP (IN of) (NP (DT each) (NN element)))))) (. .)))
Calculate the percent by mass of each element.
(ROOT (S (NP (DT The) (NN term) (NN percent) (NN composition)) (VP (VBZ means) (NP (DT the) (NN percentage)) (PP (IN by) (NP (NP (NN mass)) (PP (IN of) (NP (NP (DT each) (NN element)) (PP (IN in) (NP (DT a) (NN compound)))))))) (. .)))