( ( ( The ( first alloy ) ) ( -LRB- ( or ( ( mixture ( of metals ) ) -RRB- ) ) ) ) ( ( was ( ( bronze , ) ( which ( is ( ( a mixture ) ( of ( ( copper and ) tin ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ first) (NN alloy)) (PRN (-LRB- -LRB-) (CC or) (NP (NP (NN mixture)) (PP (IN of) (NP (NNS metals)))) (-RRB- -RRB-))) (VP (VBD was) (NP (NP (NN bronze)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (NP (NP (DT a) (NN mixture)) (PP (IN of) (NP (NN copper) (CC and) (NN tin))))))))) (. .)))
The first alloy (or mixture of metals) was bronze, which is a mixture of copper and tin.
(ROOT (S (NP (NN Bronze)) (VP (VBZ is) (NP (NP (DT an) (NN alloy)) (PP (IN of) (NP (NN copper) (CC and) (NN tin))))) (. .)))