You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, I am here to help you out. May I know your travelling dates please?

USER: Thank you. I have planned my travel dates as June 20 and June 22.

ASSISTANT: Can you please share your connection limit?

USER: Sure, I am looking for single connecting flight.

ASSISTANT: Do you have any other specifications?

USER: Yes, I would like to return in afternoon time so please make sure that.

ASSISTANT: May I know your name please?

USER: Sure, myself Katherine Campbell.

ASSISTANT: Katherine Campbell, there are no flights available in your route with your preferences.

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

ASSISTANT: Thank you for choosing us.

USER: Most welcome.