老师手把手教给俺们的啊，很珍贵的啊protectedvoidDropDownList1_SelectedIndexChanged(objectsender,EventArgse){if(this.DropDownList1.SelectedIndex==0){this.DropDownList2.Items.Clear();this.DropDownList2.Items.Add("南阳市");this.DropDownList2.Items.Add("信阳市");