You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: Can you help me to book flight ticket from AUS to BOS?

ASSISTANT: Let me know your travelling dates.

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

ASSISTANT: Do you have any preference?

USER: I would like travel in connecting flight which returns in the evening. I need an economy class.

ASSISTANT: Let me know your name.

USER: Sure, I am Jennifer Smith.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: Not a problem.

ASSISTANT: Thank you.

USER: Thank you.