33. 已知圆C1:x2+y2−4=0C_{1}:x^{2}+y^{2}-4=0C1:x2+y2−4=0与圆C2:x2+y2−4x+4y−12=0C_{2}:x^{2}+y^{2}-4x+4y-12=0C2:x2+y2−4x+4y−12=0相交于AAA,BBB两点,则两圆的公共弦∣AB∣=(\vert AB\vert =(∣AB∣=( )))