文本文件最后一行后面的CRLF

Question

请问如何避免文本文件最后一行后面出现CRLF字符？

标题LF
Start_one LF
Start_two LF
开始_三CRLF

来源：

 string s = "\nStart_";
 StringBuilder txt = new StringBuilder();
 txt.Append("Header");

 StringBuilder row = new StringBuilder();

 row.Append(s + "one");
 txt.Append(row);
 row.Clear();
 row.Append(s + "two");
 txt.Append(row);
 row.Clear();
 row.Append(s + "three");
 txt.Append(row);
 row.Clear();


 using (StreamWriter sw = File.CreateText(@"C:\Users\***\test.txt"))
 {       
     sw.WriteLine(txt.ToString());
 }