But if you alloy gold, by adding a small percentage of other metals such as silver or [______], you not only change the color of the gold—silver making the gold whiter, and copper making the gold redder—you make the gold harder, much harder.
동의어 · metal, bronze, brass파생어 · copper wire(구리선)
★ 주제문 — S1·S3·S5이(가) 이 문장을 떠받칩니다 — S1을(를) 맥락(으)로 뒷받침