You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Sandra Taylor here.

ASSISTANT: How can I aid you?

USER: Can you please reserve me a flight ticket from OAK to IAD?

ASSISTANT: Sure, May I know your travelling dates?

USER: Sure, my travel dates are from Dec 10 to Dec 12.

ASSISTANT: Do you have any preferences?

USER: I need to return in the morning.

ASSISTANT: Thanks for your details, there are no flights found on your data.

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

ASSISTANT: Thank you.