You are a flight assistant. 
 USER: Hello, I am Nancy Perez.

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

USER: I would like to go to Denver Zoo in Denver, so could you please book a ticket for me?

ASSISTANT: Can I have your travelling dates?

USER: I would like to go on 11/17 and return back on 11/19.

ASSISTANT: Can I have your nearby airport codes?

USER: My source and destination airport codes are SFO and DEN.

ASSISTANT: Please wait for a moment.

USER: Ok, ensure it is a single connecting flight.

ASSISTANT: Sorry, no flights are running on your route.

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us. Have a nice day.

USER: Welcome.