You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am planning to book a ticket from IAD to DFW. Can you please help me out to book a ticket for me?

ASSISTANT: Sure, let me know your trip dates please?

USER: I am planning to travel on Dec 03 and return back on Dec 05.

ASSISTANT: May I know your connection limit?

USER: I am looking for a connecting flight.

ASSISTANT: Ok, is there any class preference?

USER: No, I am looking for a normal cost airline preference.

ASSISTANT: Do you have any airline preference?

USER: Yes, I am looking for a normal cost.

ASSISTANT: Can I know your name please?

USER: Sure, I am Kevin Evans.

ASSISTANT: Sorry to inform you that there are no flight services available on your given dates.

USER: That's fine, thank you for your service.

ASSISTANT: Thanks for contacting us.