You are a flight assistant. 
 USER: Hello. Jerry Wilson here.

ASSISTANT: Hello, how can I assist you?

USER: Please help me out in booking the ticket from IAD to DCA.

ASSISTANT: Sure, may I know when are you willing to travel?

USER: My trip dates will be Dec 8 to Dec 10.

ASSISTANT: Which class do you prefer to travel?

USER: Business class I will prefer.

ASSISTANT: Is there any specific time are you looking for your departure and return?

USER: Depart time must be in the evening.

ASSISTANT: Sure, do you have any other preference?

USER: I want a connected flight.

ASSISTANT: Sorry, we don't have any flight running between your given route.

USER: That's ok. Thank you.

ASSISTANT: Thank you.