You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: In Philadelphia, I have some urgent work. So, please can you search for flight from DFW?

ASSISTANT: Sure, may I know your planned travel dates please?

USER: My travel dates are from 12/01 to 12/03..

ASSISTANT: Do you have any class preference?

USER: My class preference is economy class.

ASSISTANT: Would you like to travel a direct flight or a connecting flight?

USER: I want a direct flight.

ASSISTANT: Do you have any other specifications?

USER: No, thanks.

ASSISTANT: May I know your good name please?

USER: Myself Frank Hall.

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

USER: It's ok, thank you.