题目某超市一袋黑芝麻糊的包装袋上"质量"标注:500g±20g500g\pm 20g500g±20g,下列待检查的各袋黑芝麻糊中,质量不合格是( )A.450g450g450gB.515g515g515gC.490g490g490gD.505g505g505g知识点:模拟实验章节:未标注