23.已知圆C1:(x−a)2+y2=4C_{1}:(x-a)^{2}+y^{2}=4C1:(x−a)2+y2=4与C2:x2+(y−b)2=1(a,b∈R)C_{2}:x^{2}+(y-b)^{2}=1(a,b\in R)C2:x2+(y−b)2=1(a,b∈R)交于AAA,BBB两点.若存在aaa,使得∣AB∣=2\vert AB\vert =2∣AB∣=2,则bbb的取值范围为 ___[−3,3][-\sqrt{3},\sqrt{3}][−3,3]___.