You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I am Emma Campbell. I would like to book a flight ticket from DFW to SFO, can you please help me in booking?

ASSISTANT: May I know your desired travel dates please?

USER: My desired travel dates are from Sept 16 to Sept 18.

ASSISTANT: Do you have any other specifications?

USER: I would like to return in the evening. I need a connecting flight.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for opting us.