MenuStrip(主菜单)、ContextMenuStrip(右键菜单)的即时状态的获取方法

1、如何正确的显示MenuStrip某一菜单下面的复制、剪切、粘贴菜单项的即时状态：

private void mi_Edit_DropDownOpened(object sender, EventArgs e)
        {
            mi_Edit_Undo.Enabled = textBox1.CanUndo;

            mi_Edit_Copy.Enabled = textBox1.SelectionLength > 0;
            mi_Edit_Cut.Enabled = mi_Copy.Enabled;

            mi_Edit_Paste.Enabled = Clipboard.ContainsText();
        }

2、如何正确的显示ContextMenuStrip右键菜单下的复制、剪切、粘贴菜单项的即时状态： 

private void contextMenuStrip1_Opened(object sender, EventArgs e)
        {
            mi_Edit_Undo.Enabled = textBox1.CanUndo;

            mi_Copy.Enabled = textBox1.SelectionLength > 0;
            mi_Cut.Enabled = mi_Copy.Enabled;

            mi_Paste.Enabled = Clipboard.ContainsText();
        }