If you are having this kind of string then please refer this code.
protected void Page_Load(object sender, EventArgs e)
{
string question = "Hello How are you?";
string[] questionWords = question.Split(' ');
string string1 = string.Format("{0} {1} {2}", questionWords[0], questionWords[1], questionWords[2]);
string string2 = questionWords[3].Substring(0, 3);
}