You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you now?

USER: Please can you help me to book a flight ticket from IAH to OAK?

ASSISTANT: May I know your travelling dates too?

USER: Ok, please book for the dates June 18 and 20 respectively.

ASSISTANT: May I know your name to proceed further?

USER: My name is Ryan Evans.

ASSISTANT: May I know your depart and return time respectively?

USER: Ok, please book a flight which depart during afternoon and arrival time I planned is during afternoon.

ASSISTANT: Do you need a connecting flight?

USER: Yes.

ASSISTANT: Any other preferences form your side?

USER: No.

ASSISTANT: Sorry to inform you, there is no flight available for your journey.

USER: That is ok, thank you for the information provided.

ASSISTANT: Thank you for connecting with us.