You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I want to attend for a seminar in DEN. Can you please make a reservation from DCA?

ASSISTANT: May I know your trip dates?

USER: Sure, I want to travel on Oct 10 and intend to return on Oct 12.

ASSISTANT: Do you have any connecting flight preferences to travel?

USER: I need a flight with single connection.

ASSISTANT: Is there any other concern?

USER: My depart time must be in the afternoon.

ASSISTANT: Please share your name to proceed further?

USER: Sarah Nelson.

ASSISTANT: No flight found on your desired route at the moment.

USER: Ok, not an issue. Thank you for the information.

ASSISTANT: Thank you for choosing us.