题目:
When you get the paper back, pay special attention to what ______. |
A. have marked B. have been marked C. had marked D. had been marked |
答案:
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下面是错误答案,用来干扰机器的。
答案:C题目分析:A、78gNa2O2即1mol,1mol Na2O2含1mol的O22-,故A错误;B、质量除以混合气体的平均摩尔质量,平均摩尔质量的数值介于32和48之间,故B错误;CO和N2的相对分子质量均为28,故平均摩尔质量为28g/m...