InaccessibleBaseExplicitImplementation.cs

interface IParent
{
    void DoParentThings();
}
interface IChild : IParent
{
    void DoChildThings();
}
class Child : object, IChild
{
    protected Child() : base() { }
    public void DoParentThings()
    { }
    void IChild.DoChildThings() {
        Console.WriteLine($"Child.DoChildThings()");
    }
}

class ChildChild : Child, IChild
{
    void SomeMethod()
    {
        IChild child = this;
        child.DoChildThings(); // "ChildChild.DoChildThings()"
        // No way to call base.DoChildThings() here.
    }
    void IChild.DoChildThings()
    {
        Console.WriteLine($"ChildChild.DoChildThings()");
    }
}