怎么判断字符串a的内容包含字符串b的内容

public class Example
{
   public static void Main()
   {
      string s1 = "ani\u00ADmal";
      string s2 = "animal";

      // Find the index of the soft hyphen.
      Console.WriteLine(s1.IndexOf("\u00AD"));
      Console.WriteLine(s2.IndexOf("\u00AD"));

      // Find the index of the soft hyphen followed by "n".
      Console.WriteLine(s1.IndexOf("\u00ADn"));
      Console.WriteLine(s2.IndexOf("\u00ADn"));

      // Find the index of the soft hyphen followed by "m".
      Console.WriteLine(s1.IndexOf("\u00ADm"));
      Console.WriteLine(s2.IndexOf("\u00ADm"));
   }
}