You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I am Barbara Moore. Please book a ticket from DEN to DCA, to meet my family.

ASSISTANT: Sure, may I know your preferable dates to travel?

USER: Sure, my trip dates are from 03/28 and 03/30.

ASSISTANT: Sorry, there is no flight available on your requested dates.

USER: It's ok, thanks for your information.

ASSISTANT: You are most welcome.