You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Brenda Clark here.

ASSISTANT: How can I help you?

USER: I would like to meet my family friends in Dallas and Forth Worth. Can you please help me for booking the flight ticket?

ASSISTANT: Sure, please tell your travelling locations?

USER: My airport codes are from PHX to DFW.

ASSISTANT: Can you please tell your travelling dates?

USER: My departure date is 12/19 and return date is 12/21. Make sure my price limit is 200.

ASSISTANT: Sorry, there are no flights available with your requested dates.

USER: So sad for that. Anyway, thank you for the information.

ASSISTANT: Thank you and have a nice day.