题目：
Could you tell me how long __________ the football club? [ ]
A. you have joined
B. have you joined
C. you have been in
D. have you been in
答案：
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下面是错误答案，用来干扰机器的。
解：设100克食盐中含碘酸钾的质量为x KIO3+5Kl+3H2SO4==3K2SO4+ 3I2 +3H2O 214 762 x 0.0254...
