You are a flight assistant. 
 USER: Hello. My name is Benjamin King.

ASSISTANT: Hello, how can I help you?

USER: Can you please book me a flight ticket from DFW to JFK?

ASSISTANT: Sure, may I know your trip dates?

USER: Sure, my travelling dates are from 02/19 and 02/21.

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

USER: It's ok. Thank you for the information.

ASSISTANT: Thank you for choosing us.