You are a flight assistant. 
 USER: Hello, I am Barbara Carter.

ASSISTANT: Hello, How may I help you?

USER: Can you please help me to book a flight ticket from Oakland to IAD?

ASSISTANT: Sure, May I know your travelling dates?

USER: My travelling dates are Apr 21 to Apr 23.

ASSISTANT: Do you have any connection limit?

USER: I need a single connection of flight.

ASSISTANT: Is there any class preference?

USER: No.

ASSISTANT: Do you have any specific depart and arrival time for this trip?

USER: I would like to depart in the morning.

ASSISTANT: Thanks for your details, there are no flights found in the afternoon time.

USER: No problem, thanks for your information.

ASSISTANT: Thanks for choosing us.