25. 已知圆C1:x2+y2−4y=0C_{1}:x^{2}+y^{2}-4y=0C1:x2+y2−4y=0,圆C2:x2+y2−2x−2y+1=0C_{2}:x^{2}+y^{2}-2x-2y+1=0C2:x2+y2−2x−2y+1=0,则两圆的位置关系为((( )))