Writing a CSV to ftp

我有一个将数据编译在一起的Web服务，我想将其存储在CSV中，这样用户就可以获得下载链接。这就是我的

            string fileName = "Test.csv";
            string ftpAddress = "MYDOMAIN.COM";
            string username = "MYUSERNAME";
            string password = "MYPASSWORD";
            List<string[]> done = new List<string[]>();
            string[] firstline = new string[2];
            firstline[0] = "hello this is ";
            firstline[1] = "a test";
            done.Add(firstline);
            string[] secondline = new string[2];
            secondline[0] = "hello this is a ";
            secondline[1] = "second test";
            done.Add(secondline);
            string delimiter = ",";
            StringBuilder sb = new StringBuilder();

            for (int index = 0; index < 2; index++)
                sb.AppendLine(string.Join(delimiter, done[index]));
            string str = sb.ToString();
            byte[] buffer = new byte[str.Length * sizeof(char)];
            System.Buffer.BlockCopy(str.ToCharArray(), 0, buffer, 0, buffer.Length);

                WebRequest request = WebRequest.Create("ftp://" + ftpAddress + fileName);
                request.ContentType = 
                request.Method = WebRequestMethods.Ftp.UploadFile;
                request.Credentials = new NetworkCredential(username, password);
                Stream reqStream = request.GetRequestStream();
                reqStream.Write(buffer, 0, buffer.Length);

                reqStream.Close();

CSV保存正确，但我没有得到它读取的单独列

"你好，这是一个测试"
"喂，这是第二个测试"

而不是

"你好，这是"，"一个测试"
"你好，是一个"，"第二个测试"

关于如何用逗号分隔列，有什么想法吗？

        string fileName = "Test.csv";
        string ftpAddress = "MYDOMAIN.COM";
        string username = "MYUSERNAME";
        string password = "MYPASSWORD";
        
        List<string[]> done = new List<string[]>();
        string[] firstline = new string[2];
        firstline[0] = "hello this is ";
        firstline[1] = "a test";
        done.Add(firstline);
        string[] secondline = new string[2];
        secondline[0] = "hello this is a ";
        secondline[1] = "second test";
        done.Add(secondline);
        string delimiter = @""",""";
        StringBuilder sb = new StringBuilder();
        foreach (var lineArray in done)           
            sb.AppendLine(string.Format(@"""{0}""", string.Join(delimiter, lineArray)));
        string str = sb.ToString();
        byte[] buffer = new byte[str.Length * sizeof(char)];
        System.Buffer.BlockCopy(str.ToCharArray(), 0, buffer, 0, buffer.Length);
        WebRequest request = WebRequest.Create("ftp://" + ftpAddress + fileName);
        request.ContentType =
        request.Method = WebRequestMethods.Ftp.UploadFile;
        request.Credentials = new NetworkCredential(username, password);
        Stream reqStream = request.GetRequestStream();
        reqStream.Write(buffer, 0, buffer.Length);
        reqStream.Close();

string delimiter = @""";""";