Передача в качестве параметра списка унаследованных объектов

        private AbstractPlace random_place(List<AbstractPlace> a_places, AbstractPlace exept)
        {
            List<AbstractPlace> list = new List<AbstractPlace>();
            list.Add(exept);
            return random_place(a_places, list);
        }

random_place(roads, road)

public List<Road> roads;

    public class Road : AbstractPlace
    {
        public Road(AbstractWorld a_world) : base(a_world)
        {
        }
 
    }

random_place(roads, road)

private AbstractPlace random_place<T>(List<T> a_places, T exept) where T :  AbstractPlace
{   }

static readonly Random rand = new Random();
private AbstractPlace random_place(IEnumerable<AbstractPlace> a_places, params AbstractPlace[] exeptions)
{
   var filteredList = a_places.Except(exceptions);
   return filteredList.ElementAt(rand.Next(filteredList.Count()));
}

connect_roads(random_place(roads, road), road);

connect_roads(random_place(roads, road) as Road, road);

        private AbstractPlace random_place<T>(List<T> a_places, AbstractPlace exept) where T : AbstractPlace
        {
            AbstractPlace[] list = new AbstractPlace[1];
            list[0]=exept;
            return random_place(a_places, list);
        }
 
 
        private AbstractPlace random_place(IEnumerable<AbstractPlace> a_places, params AbstractPlace[] exeptions)
        {
            /*List<AbstractPlace> places_for_random = a_places.FindAll(
                delegate (AbstractPlace item1)
                {
                    return !exept.Exists(
                        delegate (AbstractPlace item2)
                        {
                            return item1 == item2;
                        });
                });
            return places_for_random[Core.rnd.Next(places_for_random.Count - 1)];*/
 
            var filteredList = a_places.Except(exeptions);
            return filteredList.ElementAt(Core.rnd.Next(filteredList.Count()));
        }

        private AbstractPlace random_place(IEnumerable<AbstractPlace> a_places, AbstractPlace exept) 
        {
            AbstractPlace[] list = new AbstractPlace[1];
            list[0]=exept;
            return random_place(a_places, list);
        }

private AbstractPlace random_place<T>(List<T> a_places, params T[] exeptions) where T : AbstractPlace
        {
            var filteredList = a_places.Except(exeptions);
            return filteredList.ElementAt(Core.rnd.Next(filteredList.Count()));
        }