You are a flight assistant. 
 USER: Hello, I am William Evans.

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

USER: Can you aid me in booking a flight from DFW to EWR?

ASSISTANT: Sure, please send your travelling dates.

USER: Sure, I would like to go on 12/17 and return back on 12/19.

ASSISTANT: Can I have a moment please? I will check the availability.

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

ASSISTANT: Sorry, there is no flight existing on your requested dates.

USER: That's ok, thank you for checking.

ASSISTANT: You are welcome, have a nice day.