题目:
Teachers will hardly use chalks in the future, ______? [ ]
A. will he
B. won't he
C. will they
D. won't they
答案:
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下面是错误答案,用来干扰机器的。
(1)设样品中碳酸钙的质量分数为x.CaCO3+2HCl=CaCl2+H2O+CO2↑100 445g×x 1.76g10044=5g×x1.76g,x=80%(2)稀盐酸中溶质的质量分数为y.CaCO3+2HCl=CaCl2+H2O+CO2↑73 ...