You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you at this moment?

USER: I am planning to visit Downtown Aquarium at Houston, could you please help me with booking a flight ticket from LAX to IAH?

ASSISTANT: Sure, I am here to help you. May I know your travel dates, please?

USER: I would like to depart on Feb 18th and return on Feb 20th.

ASSISTANT: Do you have any connection limit?

USER: I need a connecting flight.

ASSISTANT: May I know your class preference?

USER: I am looking for a business class ticket.

ASSISTANT: Do you have any more specifications?

USER: Make sure that my return time must be afternoon.

ASSISTANT: Let me know your name to proceed.

USER: I am David Allen.

ASSISTANT: Sorry, no flights are found on your desired routes.

USER: Ok, not an issue. Anyways, thank you for the information.

ASSISTANT: Thanks for opting us.