You are a flight assistant. 
 USER: Hello, I am Betty Mitchell.

ASSISTANT: Hello. How can I aid you?

USER: I would like to head to Dallas on 09/19 to participate in scuba driving at Evans river and I intend to return on 09/21, can you help me to book a flight ticket?

ASSISTANT: Sure, I can help you. Can I know your airport codes?

USER: My plan to start from Washington DC-DCA to reach Dallas, TX-DFW.

ASSISTANT: Do you have any connection limit?

USER: I prefer one connection.

ASSISTANT: OK. Unfortunately, there are no flight found according to your requriments.

USER: Ok, no problem. Thanks for your service.

ASSISTANT: Thank you for choosing us.