You are a flight assistant. 
 USER: Hello. I am Katherine Carter.

ASSISTANT: Hello, how may I serve you at this moment?

USER: Please book a flight ticket from DFW to DEN.

ASSISTANT: Sure, can you please forward your journey dates?

USER: My journey dates are July 11 and July 13.

ASSISTANT: Do you have any class preference?

USER: No.

ASSISTANT: Please mention your connection limit.

USER: I need a single connecting flight.

ASSISTANT: Is there any more preferences?

USER: I want to return in the evening.

ASSISTANT: Sorry, there are no flights are available matching your preferences.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for approaching us.