private async void Enable_PastParticipleBase(object sender, EventArgs e)
        {
            DisableAllRadios();
            Verbs.Children.Clear();
            Verbs.ForceLayout();
            TestButton.IsEnabled = true;

            foreach (var item in await content.Fill_Partially(FVWord.WordGiven.pastParticiple))
            {
                Verbs.Children.Add(item);
            }
        }
        private async void Enable_InfitiveBase(object sender, EventArgs e)
        {
            DisableRadio();         //because it has 1st index of RadioButtons it seems it must call this method synchronusly

            Verbs.Children.Clear();
            Verbs.ForceLayout();
            TestButton.IsEnabled = true;

            foreach (var item in await content.Fill_Partially(FVWord.WordGiven.infinitive))
            {
                Verbs.Children.Add(item);
            }
        }