You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I am Carolyn Collins. Can you please assist me in booking my flight ticket from IAD to DEN?

ASSISTANT: Sure, may I know your planned travel dates please?

USER: My travelling dates are Feb 28 and Mar 01.

ASSISTANT: Do you have any particular time for departing and returning?

USER: I want my return ticket at evening time.

ASSISTANT: Would you like to prefer direct flight or connecting flight?

USER: I need connecting flight.

ASSISTANT: Sorry, there is no flight available in this route.

USER: Ok, fine thank you for checking.

ASSISTANT: You are welcome.