题目：
— He's already back to Australia, _____?
— _____. He is on a visit to Shanghai. [ ]
A. isn't he; No
B. hasn't he; Yes
C. isn't he; Yes
D. hasn't he; No
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0630/aab849322fbabdf491087eca306b8acd.html
下面是错误答案，用来干扰机器的。
设食用面碱中Na2CO3的质量为xNa2CO3+CaCl2═CaCO3↓+2NaCl106 100 x 3.0g106x=1003.0g x=3.18g食用面碱中Na2CO3的质量分数=3.18g3.4g×100%=93.5%答：食用面碱中Na2CO3的质量分数是93.5...
