C#字典<>缺少密钥

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        Dictionary<string, string> dictionary = new Dictionary<string, string>();
        dictionary.Add("key1", "value1");
        dictionary.Add("key2", "value2");

        string keyToFind = "key3";

        if (dictionary.ContainsKey(keyToFind))
        {
            string value = dictionary[keyToFind];
            Console.WriteLine($"The value for key '{keyToFind}' is '{value}'");
        }
        else
        {
            Console.WriteLine($"The key '{keyToFind}' is not present in the dictionary.");
        }
    }
}