Hi.
user
Hello, how may I help you?
assistant
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?
user
Sure, may I know your source and destination airport codes please?
assistant
Yes, my airport codes are CO-DEN and DC-IAD.
user
Please wait for a moment.
assistant
  Ok.
user
Sorry, there is no flight available on your requested dates.
assistant
That's ok, thank you for the response.
user
You are most welcome.
assistant