//设置listbox可以选择多个子项
            listBox1.MultiColumn = true;
            listBox1.SelectionMode = SelectionMode.MultiSimple;
        }

 //listbox是一个列表，用户可选择一或多个子项
        private void button1_Click(object sender, EventArgs e)
        {
            //添加子项到listbox
            listBox1.Items.Add("添加到listbox1的子项1");

           
            //删除子项从listbox

        }
        //删除子项从listbox
        private void button2_Click(object sender, EventArgs e)
        {
            if (listBox1.Items.Count==0)
            {
                MessageBox.Show("listbox无子项，不能删除");
            }
            else
            {
                listBox1.Items.Remove(listBox1.SelectedItem);
                MessageBox.Show("listbox删除子项成功");
            }

        }