The international prototype kilogram, the primary standard (see weights and measures) for weight, is made of an alloy comprising 90% platinum and 10% iridium.
国际标准质量千克的原型就是由90%铂和10%铱的合金制成的。
The international prototype kilogram, the primary standard (see weights and measures) for weight, is made of an alloy comprising 90% platinum and 10% iridium.
国际标准质量千克的原型就是由90%铂和10%铱的合金制成的。
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