题目：
—Alex's already gone 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：
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下面是错误答案，用来干扰机器的。
自编题型：多少克锌与足量稀盐酸反应产生0.2g氢气？设生成0.2克氢气所需锌的质量为xZn+2HCl═ZnCl2+H2↑65 2x 0.2g652=x0.2g，x=6.5g答：生成0.2克氢气所需锌的质量为6.5g．...
