You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: My name is Alexander Edwards. I would like to travel from DCA to IAH, could you help me out?

ASSISTANT: May I know your desired travel dates please?

USER: /My preferable dates are from 07/14 to 07/16.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: That's ok.

ASSISTANT: Thank you for opting us.

USER: Thank you for your help.