将值从字典对象写入文本文件只写入最后一个键值对

我完全不懂 C# 或任何编程，但我想学习。过去几天我一直在网上搜索，将应该从 2 个文本文件中读取的内容放在一起并输出一个文件（格式为 json 文件，我只需将其复制/粘贴到该文件中）。所以我可以从两个文件中读取，创建一个字典对象并写入一个文件，但它只写入最后一个项目。我相信我会一遍又一遍地覆盖直到最后一部分。如何附加到文件而不是覆盖？

我的代码：

using System.IO;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WriteLangFile
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                string path1 = @"C:\temp\langVars.txt";
                string path2 = @"C:\temp\langValues.txt";

                string[] readVars = File.ReadAllLines(path1);
                string[] readVals = File.ReadAllLines(path2);

                Dictionary<string, string> dictionaryVars = new Dictionary<string, string>();
                for (int i = 0; i < readVars.Length; i++)
                {
                    dictionaryVars.Add(readVars[i], readVals[i]);
                }

                string outputPath = ("C:\\temp\\");
                string outputFileName = ("lang.txt");
                string constant, value;

                foreach (KeyValuePair<string, string> kvp in dictionaryVars)
                {
                    constant = (kvp.Key);
                    value = (kvp.Value);
                    string[] lines = { ("\"LANG_\"" + constant + "\"_LANG \"" + " : { "),
                                       ("\"translations\" : {"),
                                       ("\"Lang.asp\" : {"),
                                       ("\"eng\"" + ": \"" + value + "\""),
                                       ("}"),
                                       ("}"),
                                       ("},")
                    };

                    using (StreamWriter outFile = new StreamWriter(Path.Combine(outputPath, outputFileName)))
                    {
                        foreach (var item in lines)
                        {
                            outFile.WriteLine(item.ToString());
                        }

                    }

                }
            }
            catch (Exception e)
            {
                Console.WriteLine("Exception: " + e.Message);
            }
            finally
            {
                Console.WriteLine("Executing finally block.");
            }
        }
    }
}