如何替换KeyValuePair<> List<>中的元素

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<KeyValuePair<string, int>> keyValuePairs = new List<KeyValuePair<string, int>>();
        keyValuePairs.Add(new KeyValuePair<string, int>("A", 1));
        keyValuePairs.Add(new KeyValuePair<string, int>("B", 2));
        keyValuePairs.Add(new KeyValuePair<string, int>("C", 3));

        // 查找要替换的元素的索引位置
        int index = keyValuePairs.FindIndex(pair => pair.Key == "B");

        if (index != -1)
        {
            // 创建新的键值对对象进行替换
            KeyValuePair<string, int> newKeyValuePair = new KeyValuePair<string, int>("D", 4);

            // 替换元素
            keyValuePairs[index] = newKeyValuePair;

            Console.WriteLine("替换后的List<>内容：");
            foreach (var pair in keyValuePairs)
            {
                Console.WriteLine($"Key: {pair.Key}, Value: {pair.Value}");
            }
        }
        else
        {
            Console.WriteLine("未找到要替换的元素。");
        }
    }
}