A:明矾溶液加热
B:CH3COONa溶液加热
C:氨水中加入少量NH4Cl固体
D:小苏打溶液中加入少量NaCl固体
抛物线y=3(x-4)2+1的对称轴是直线( )
________ volunteers will give out leaflets to ask people to protect the wetlands.