You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: Can you  please book a flight ticket from IAD to LAS?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: Thank you. I have planned my travel  dates as Dec 17 and Dec 19.

ASSISTANT: Ok, could I have your name please?

USER: Sure, myself Angela Moore.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I am  looking for single connecting flight.

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

USER: Oh! It is sad to hear. Anyway, thank you for your  time.

ASSISTANT: You are welcome, have a great day.