12] B
11] C
A如NaHSO4+H2SO4(浓)→HCl、B如NaOH+NaHCO3或Ca(OH)2+Na2CO3、D如铝盐与氨水
10] CD
9] B
8] D
7] D
6] D
5] B
4] D ①③④
3] AD