You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: My name is Kevin Parker.

ASSISTANT: How may I guide you?

USER: I need to book a flight ticket from DCA to SFO. Please help me in booking a flight ticket.

ASSISTANT: Kevin Parker, may I know your travelling dates?

USER: My journey dates are from 08/10 to 08/12.

ASSISTANT: Do you have any specifications?

USER: I need to depart in the evening and I need a connecting flight.

ASSISTANT: Sorry, there are no flights available for your journey.

USER: No problem, thanks for your information.

ASSISTANT: Have a nice day.