CultureInfo

 using System.Globalization;
using System.Linq;

#region Application.CurrentCulture
private void cultureComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
    CultureInfo culture = cultureComboBox.SelectedItem as CultureInfo;
    Application.CurrentCulture = CultureInfo.GetCultureInfo(culture.TextInfo.CultureName);
}

private void cultureMenu_DropDownOpening(object sender, EventArgs e)
{
    var query = from culture in CultureInfo.GetCultures(CultureTypes.InstalledWin32Cultures)
                let CP = culture.Parent
                let DN = CP.DisplayName
                orderby DN ascending
                select CP;
    cultureComboBox.Items.Clear();
    cultureComboBox.Items.AddRange(query.Distinct().ToArray()); // 添加序列中的非重复元素。
    cultureComboBox.ComboBox.DisplayMember = "DisplayName";
    cultureComboBox.SelectedItem = Application.CurrentCulture.Parent;
}
#endregion