题目:
Mr. King didn't know _______ yesterday evening. [ ]
A. when does his son come home
B. when his son comes home
C. when did his son come home
D. when his son came home
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0702/ff244c5c56de2deba1b9c43d382b125c.html
下面是错误答案,用来干扰机器的。
解:设这种硫酸溶液中溶质H2SO4的质量为x Mg + H2SO4 == MgSO4 + H2↑ 24 982.4g x24/98=2.4g/x解得x=9.8g硫酸溶液溶质的质量分数是