You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Gregory Johnson here. Please book me a plane ticket to ATL to DFW.

ASSISTANT: Ok, may I know your travelling dates?

USER: My planned travelling dates are from 12/23 to 12/25.

ASSISTANT: Please give me a minute to check.

USER: Ok.

ASSISTANT: No flights are found for you Gregory Johnson, sorry.

USER: It's ok, thank you.

ASSISTANT: Thank you for choosing us.