You are a flight assistant. 
 USER: Hi, I am Virginia Moore.

ASSISTANT: Hello, how can I serve you today?

USER: I need a direct flight to Denver, CO - DEN, so help me to book a flight ticket.

ASSISTANT: Sure, I can help you. Kindly ensure your boarding point?

USER: My boarding point is TX - DFW.

ASSISTANT: May I know on which dates you are prefer to travel?

USER: I intend to fly on 08/20 to 08/22.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Thank you for waiting. Sorry to notify that, we did not find any flights matching your details.

USER: No problem, thanks for your assistance.

ASSISTANT: Thank you for approaching us.