You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you today?

USER: Can you please book a ticket for me from IAH to SFO?

ASSISTANT: Sure, will you please mention your preferable dates of travelling?

USER: My trip is in Aug from 17th to 19th.

ASSISTANT: Do you have any connection limit?

USER: No, I prefer to travel on a direct flight.

ASSISTANT: Can I know your name to book the flight ticket?

USER: Donald Moore here.

ASSISTANT: Any other preferences do you have?

USER: No, thanks for asking.

ASSISTANT: Please wait a moment to check the flights.

USER: Sure, take your time.

ASSISTANT: I am sorry to inform you that, none of the airlines is providing a flight on your travel dates and locations to book a flight ticket.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for reaching to our services, hope you have a great day.