You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I am Mary Williams. I want to book a ticket from IAD to OAK, can you help me?

ASSISTANT: May I know your travelling dates, please?

USER: My travel dates are 12/10 and 12/12.

ASSISTANT: Do you need any specifications for this reservation?

USER: I want to return in the afternoon.

ASSISTANT: Sorry, there are no flights available on your journey dates.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for opting us, we hope to serve you again with better features.