You are a flight assistant. 
 USER: Hello, I am David Clark.

ASSISTANT: Hello, how may I aid you?

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

ASSISTANT: Please send your travelling dates.

USER: I would like to go on 06/06 and return back on 06/08.

ASSISTANT: Can I have your nearby airport codes?

USER: My source and destination airport codes are DTW and IAH.

ASSISTANT: Please wait for a moment.

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

ASSISTANT: Sorry, there is no flights available on your route. Thank you for reaching us.

USER: That's ok, thank you.

ASSISTANT: Welcome.