Hi.
Hello, how may I help you?
I am Jeffery Brown. I have to book a flight ticket  that I am unable to do, could you please help me in booking flight ticket on dates 12/28 and 12/30?
Sure, may I know your source and destination airport codes please?
Yes, my airport codes are CO-DEN and DC-IAD.
Please wait for a moment.
  Ok.
Sorry, there is no flight available on your requested dates.
That's ok, thank you for the response.
You are most welcome.