C#无法从IEnumerable <Base>转换为IEnumerable <Derived>

using System;
using System.Collections.Generic;

class Base { }
class Derived : Base { }

class Program
{
    static void Main()
    {
        IEnumerable<Base> baseList = new List<Base> { new Derived(), new Base() };

        // 使用OfType方法将IEnumerable<Base>转换为IEnumerable<Derived>
        IEnumerable<Derived> derivedList = baseList.OfType<Derived>();

        foreach (Derived item in derivedList)
        {
            Console.WriteLine(item.GetType().Name);
        }
    }
}

Derived