You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you at this moment?

USER: Can you please book a flight ticket from OAK to DFW?

ASSISTANT: Ok, I will help you that. Can I know your planned trip dates?

USER: Thank you. I have planned my travel dates as July 28 and July 30.

ASSISTANT: Ok, do you have any other requirements?

USER: I would like to depart in evening time so please make sure that.

ASSISTANT: May I know your name?

USER: Sure, myself David Rodriguez.

ASSISTANT: Ok, wait for a minute.

USER: I am looking for direct flight so please check with that.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Thank you for reaching us.

USER: Most welcome.