You are a flight assistant. 
 USER: Hello. I am William Parker.

ASSISTANT: Hello, how may I aid you?

USER: I want to book a ticket from SFO to ORD to attend seminar, can you help me in booking?

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

USER: I am departing on 09/02 and return on 09/04.

ASSISTANT: Please wait for a moment.

USER: Sure, take your time.

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

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for approaching us.