You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I would like to attend Environmental Science Conferences in Lawrence Hall of Science at Philadelphia, PHL. So, please book me a flight ticket from Chicago, ORD.

ASSISTANT: Sure. When would you like me to book a ticket?

USER: My preferable dates are 07/25 and 07/27.

ASSISTANT: May I know your good name?

USER: Yes, I am Nicole Lopez.

ASSISTANT: Thanks for sharing the details, wait a while.

USER: Ok.

ASSISTANT: Thank you for your time. There are no flights found on your dates.

USER: No issue, thank you.

ASSISTANT: Thank you for availing us.