( Bronze ( ( ( ( is ( ( an alloy ) ( of ( ( copper and ) tin ) ) ) ) , ) ( while ( steel ( is ( ( an alloy ) ( of ( iron ( , ( carbon ( and ( other additives ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NN Bronze)) (VP (VBZ is) (NP (NP (DT an) (NN alloy)) (PP (IN of) (NP (NN copper) (CC and) (NN tin)))) (, ,) (SBAR (IN while) (S (NP (NN steel)) (VP (VBZ is) (NP (NP (DT an) (NN alloy)) (PP (IN of) (NP (NN iron) (, ,) (NN carbon) (CC and) (JJ other) (NNS additives)))))))) (. .)))
Bronze is an alloy of copper and tin, while steel is an alloy of iron, carbon and other additives.
(ROOT (S (NP (NN Bronze)) (VP (VBZ is) (NP (NP (DT an) (NN alloy)) (PP (IN of) (NP (NN copper) (CC and) (NN tin))))) (. .)))