16．（2022•宝山区模拟）已知集合S={x∣x=a+biS=\{x\vert x=a+biS={x∣x=a+bi，aaa，b∈Z}b\in Z\}b∈Z}，iii是虚数单位，对任意x1x_{1}x1，x2∈Sx_{2}\in Sx2∈S(x1(x_{1}(x1，x2x_{2}x2可以相等）均有x1x2∈S\frac{{x}_{1}}{x{}_{2}}\in Sx2x1∈S，则符合条件的元素个数最多的集合S=S=S=___{1\{1{1[，]−1-1−1[，]iii[，]−i}-i\}−i}___．