条形码扫描器已广泛应用于商业、邮政、交通等行业，在条形码扫描器内有由发光二极管、光敏二极管等元件组成的电路．这些元件都是由_1材料制成的．_刷题宝

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条形码扫描器已广泛应用于商业、邮政、交通等行业，在条形码扫描器内有由发光二极管、光敏二极管等元件组成的电路．这些元件都是由____材料制成的．

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