You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I am Patricia Thomas from Oakland. Can you please book a flight form OAK to IAD?

ASSISTANT: Sure, tell me your travel dates please?

USER: Sure, I want to depart on Sept 20 and need to return on Sept 22.

ASSISTANT: May I know your departure and return time please?

USER: Yes, my return flight must be in the morning time.

ASSISTANT: Do you have any other preferences?

USER: I need a connecting flight to travel.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: Sorry there no flights available in the morning time.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you.