You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am William Wright.

ASSISTANT: How can I help you?

USER: I need to attend a seminar at Houston, can you help me to book a flight ticket from LAX to HOU?

ASSISTANT: Let me know your travel dates.

USER: My preferable journey dates are June 17 and June 19.

ASSISTANT: Do you have any preference?

USER: I would like to return in the evening.

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

USER: No problem, thank you for the information.

ASSISTANT: Thank you.