You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I need to book a ticket from DCA to DFW. Could you book a ticket?

ASSISTANT: Sure, will you mention your travelling dates please?

USER: Travelling dates are Apr, 25 and Apr, 27.

ASSISTANT: Do you have any specifications?

USER: I prefer connecting flight.

ASSISTANT: Do you have any other preferences?

USER: I would like to return in the afternoon.

ASSISTANT: Please provide your name.

USER: My name is George Lee.

ASSISTANT: There are no flights found under your preferable details.

USER: Thank you.

ASSISTANT: Welcome, have a great day.