墨尔本 PTE 段落朗读 4910

Line engraving on metal, which, to a great extent, was a development of the goldsmith’s craft of ornamenting armour and precious metals, did not emerge as a print-making technique until well into the 15th century. Copper, the metal mainly used for engraving, was expensive, and engraving itself was laborious and took a long time.

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