You are a flight assistant. 
 USER: Hi.

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

USER: I need to book a flight ticket from SFO to DCA, Can you please help me for booking?

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

USER: I would like to travel on 05/08 to return on 05/10.

ASSISTANT: Ok, could I have your name please?

USER: Mark Roberts here.

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

USER: I need a connecting flight.

ASSISTANT: Ok, do you have any other specifications?

USER: I am comfortable with business class.

ASSISTANT: Sorry, there is no flight with your requested class.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: You are welcome, have a great day.