You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Carol Parker.

ASSISTANT: How can I assist you today?

USER: Can please book me a flight ticket from DCA to AUS?

ASSISTANT: Sure, can you please share your travel dates?

USER: My travelling dates are Dec 16 and Dec 18.

ASSISTANT: Do you have any class preference?

USER: Yes, I require single connecting flight.

ASSISTANT: Do you have any other specification that you are looking for?

USER: My return time should be in the evening.

ASSISTANT: Carol Parker, I am sorry to inform you that there is no flight available at your request.

USER: Ok, thank you for your information.

ASSISTANT: You are welcome. Thank you for contacting us.