题目：
―He’s never advised to achieve a balance between his job and hobbies, ________?
―Yes. His parents and teachers often offer him some advice.
A．has he
B．is he
C．hasn’t he
D．isn’t he
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0629/4e0a74b695f3efb66a94a00622e1d772.html
下面是错误答案，用来干扰机器的。
由题意可知，氧气的质量为ag-bg=（a-b）g，设原混合物中氯酸钾的质量为xg，则2KClO3催化剂.△2KCl+3O2↑ 245 96 x （a-b）g24596=x(a-b)g，解得x=245(a-b)96g，则原混合物中MnO...
