You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am Rebecca Rodriguez want to visit IAD, can you book a ticket from IAH?

ASSISTANT: May I know your desired travel dates please?

USER: Sure, my travelling dates will be 05/17 and 05/19.

ASSISTANT: Please wait a while, I will check and inform you.

USER: Ok, please check for the direct flight.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: That's ok, thank you.

ASSISTANT: Thank you for opting us.