// 已测试多个版本语言
            content.Append("大家一起来");
            content.Append("Come on everybody");
            content.Append("모두 들 어 서");
            content.Append("Έρθει σε όλους");
            content.Append("Vamos lá pessoal");
            var contentBytes = Encoding.GetEncoding("utf-8").GetBytes(content.ToString());

            // 这里的代码完美解决非英文乱码的问题
            var outputBytes = new byte[contentBytes.Length + 3];
            outputBytes[0] = (byte)0xEF;
            outputBytes[1] = (byte)0xBB;
            outputBytes[2] = (byte)0xBF;
            Array.Copy(contentBytes, 0, outputBytes, 3, contentBytes.Length);
            return this.File(outputBytes, "text/csv", "test.csv");