You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you now?

USER: I need your help to book a flight ticket from DCA to HOU. Can you please do that for me?

ASSISTANT: Sure, can I have your travel dates please?

USER: Thank you for accepting my request. The travel dates are Nov 1st and Nov 3rd.

ASSISTANT: Ok, please let me know your preferences about class.

USER: I prefer an economy class flight to travel.

ASSISTANT: Do you have any other specifications?

USER: I prefer a single connecting flight.

ASSISTANT: Can I have your good name please?

USER: Sure, my name is Elizabeth Miller.

ASSISTANT: Sorry to inform you that no flight is available to you on your planned  dates.

USER: It's ok, anyways thank you for your time.

ASSISTANT: Thank you for choosing us, have a good day.

USER: Most welcome.