如何使IEnumerable <T>只读？

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

public class Program
{
    public static void Main()
    {
        // 创建一个普通的 List<T>
        List<int> list = new List<int> { 1, 2, 3, 4, 5 };

        // 将 List<T> 转换为只读的 ReadOnlyCollection<T>
        ReadOnlyCollection<int> readOnlyCollection = new ReadOnlyCollection<int>(list);

        // 尝试修改只读集合将引发 NotSupportedException
        try
        {
            readOnlyCollection[0] = 99;
        }
        catch (NotSupportedException ex)
        {
            Console.WriteLine("尝试修改只读集合将引发 NotSupportedException: " + ex.Message);
        }

        // 输出只读集合的内容
        foreach (int item in readOnlyCollection)
        {
            Console.WriteLine(item);
        }
    }
}