( ( calculate ( ( the ( mass ( percent composition ) ) ) ( of ( iron ( for ( each ( iron ore ) ) ) ) ) ) ) ... )
(ROOT (S (VP (VB calculate) (NP (NP (DT the) (JJ mass) (NN percent) (NN composition)) (PP (IN of) (NP (NP (NN iron)) (PP (IN for) (NP (DT each) (NN iron) (NN ore))))))) (: ...)))
calculate the mass percent composition of iron for each iron ore ...
(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)))))))) (. .)))