You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: My name is Alexander Johnson, I want to book a flight from DCA to BOS. Can you help me?

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

USER: I will fly on Feb 1st and return on Feb 3rd.

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

USER: I need a depart flight in evening.

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

USER: I need a connecting flight.

ASSISTANT: Do you have any other specifications?

USER: No.

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

USER: Ok, thank you for the information.

ASSISTANT: You are welcome.