You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I would like to visit Charlotte to meet my sister, please help me in booking a ticket from DCA to CLT.

ASSISTANT: Sure, may I know your trip dates please?

USER: My planned trip dates are on Apr 8 and Apr 10.

ASSISTANT: Do you have any other requirements?

USER: I would like to return in the evening.

ASSISTANT: Can I know your name please?

USER: My name is Jennifer Hall.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Most welcome.