问C# File.WriteAllText不区分大小写吗？

EN

public static bool FileExistsCaseSensitive(string filename)
        {
            string name = Path.GetDirectoryName(filename);
            return name != null && Array.Exists(Directory.GetFiles(name), s => s == Path.GetFullPath(filename));
        }

public void GetProWords(string word)
        {
            WordDataSet.Clear();
            Words.Clear();
            Frequency.Clear();
            string[] WordSet;

            string fname = Environment.CurrentDirectory + "\\Brain\\Pro-" + word + ".txt";
            if (FileExistsCaseSensitive(fname))
            {

            }
            else
            {
                File.WriteAllText(fname, "");
            }

            TextReader txtReader = new StreamReader(fname);
            try
            {
                while (txtReader.Peek() != -1)
                {
                    string line = txtReader.ReadLine();
                    if (line.Contains('~'))
                    {
                        WordSet = line.Split('~');
                        Words.Add(WordSet[0].ToString());
                        Frequency.Add(Convert.ToInt32(WordSet[1]));
                    }
                }
                for (int i = 0; i < Words.Count; i++)
                {
                    WordDataSet.Add(new WordData { Word = Words[i], Frequency = Frequency[i] });
                }
            }
            finally
            {
                txtReader.Close();
            }
        }