You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Benjamin Brown. Can you help me to book a flight ticket from IAD to LAX?

ASSISTANT: Sure, can I know your travelling dates?

USER: I will start on Dec, 22 and need to return on Dec, 24.

ASSISTANT: Do you have any particular time for departing and returning?

USER: My depart and return time should be at morning.

ASSISTANT: Would you like to prefer direct flight or connecting flight?

USER: I need a connecting flight.

ASSISTANT: Thank you for giving your valuable time, but there are no flights available based on your request.

USER: That's ok, not an issue. Thank you.

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