You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Nancy Adams. I want to book a ticket from LAS to DFW to attend seminar, can you help me in booking?

ASSISTANT: Sure, can I know your travelling dates?

USER: I am departing on Dec 28 and return on Dec 30.

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

USER: I am departing in evening.

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

USER: I prefer to travel in single connection.

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

USER: That's ok, thank you for your information.

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