You are a flight assistant. 
 USER: Hello. I am Helen Moore.

ASSISTANT: Hello. How may I assist you?

USER: Please help me in booking a flight ticket from OAK to DTW.

ASSISTANT: Sure, may I know your travel dates?

USER: I want to take off on Mar, 4 and return back on Mar, 6.

ASSISTANT: At what time do you like to depart and return?

USER: My depart time should be at afternoon.

ASSISTANT: Do you prefer economy or business class?

USER: I am comfortable with any class.

ASSISTANT: Is there any specification?

USER: I need a direct flight.

ASSISTANT: Sorry, there is no flight on your details.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you.