C# WinForm CheckedListBox实现RadioButton的单选且不可取消单选的效果

//加入ItemCheck方法
this.cblChangeMode.ItemCheck += new System.Windows.Forms.ItemCheckEventHandler(this.SelectOne);

//加入控制是否继续的全局变量，防止进入死循环
public bool canContinue = true;
private void SelectOne(object sender, ItemCheckEventArgs e)
{
            CheckedListBox clb = sender as CheckedListBox;
            //勾选原选项
            if (clb.CheckedIndices.Count > 0 && clb.CheckedIndices[0] == e.Index && canContinue )
            {
                e.NewValue = CheckState.Checked;
            }
            //第一次勾选
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