∵等腰△ABC中，AB=AC，∠A=40°，∴∠ABC=∠C= 180°?∠A 2 =70°，∵线段AB的垂直平分线交AB于D，交AC于E，∴AE=BE，∴∠ABE=∠A=40°，∴∠CBE=∠ABC-∠ABE=30°．故选：D．
