( ( ( ( Bronze , ) ( ( an alloy ) ( of ( ( copper and ) tin ) ) ) ) , ) ( ( was ( ( the ( first alloy ) ) known ) ) . ) )
(ROOT (S (NP (NP (NN Bronze)) (, ,) (NP (NP (DT an) (NN alloy)) (PP (IN of) (NP (NN copper) (CC and) (NN tin)))) (, ,)) (VP (VBD was) (NP (NP (DT the) (JJ first) (NN alloy)) (VP (VBN known)))) (. .)))
Bronze, an alloy of copper and tin, was the first alloy known.
(ROOT (S (NP (NN Bronze)) (VP (VBZ is) (NP (NP (DT an) (NN alloy)) (PP (IN of) (NP (NN copper) (CC and) (NN tin))))) (. .)))