You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Can you help me to book a flight ticket from DTW to DCA?

ASSISTANT: Sure, can I know your travelling dates?

USER: My travelling dates are 29 and 31 of May.

ASSISTANT: Do you have any other specifications?

USER: I prefer to travel in business class with a connecting flight.

ASSISTANT: May I know your name?

USER: I am Shirley Turner.

ASSISTANT: Sorry, there are no flights available on your travelling dates.

USER: It's ok, not a problem, thank you.

ASSISTANT: Thank you for choosing us.