• 您可以使用String.Contains Method和String.Substring Method来执行此操作。
• 密码：*

string stringfromtheinput = "Sentence blah blah blahh because bblahhh balh and blahhh";
String[] spearator = {
  "because",
  "and",
  "now",
  "this is"
};

foreach(string x in spearator) {
  if (stringfromtheinput.Contains(x)) {
    Console.WriteLine(stringfromtheinput.Substring(stringfromtheinput.LastIndexOf(x)));
  }
}

• 输出：*

because bblahhh balh and blahhh
and blahhh

你可以试着找到\because\and\now\this is的位置，然后使用substring。

string StringFromTheInput = TextBox1.Text;
 string str="";
            var match = Regex.Match(s, @"\b(because|and|now|this is)\b");
            if (match.Success)
            {
                var index=match.Index; // 25
                str = s.Substring(index);//str is what you want
            }

输出量：

because bblahhh balh and blahhh