强调稀的或是浓的:
Zn+H2SO4(稀)=H2（气体）+ZnSO4等
Zn+2HCl(稀)=H2（气体）+ZnCl2等
Zn+2H2SO4(浓)(微热)=ZnSO4+SO2（气体）+2H20
Cu+2H2SO4(浓)(加热)=CuSO4+SO2（气体）+2H20等