You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am Justin Adams. I want to go to Philadelphia next week for my film shooting purpose, can you please book a flight ticket for me?

ASSISTANT: May I know your desired travel dates please?

USER: I planned my trip from 04/19 to 04/21.

ASSISTANT: Can I know your preferred airport codes please?

USER: My source is IAD and landing airport code is PHL.

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

USER: Can you re-check once, as it's an emergency?

ASSISTANT: No way, there is no flight available, I am sorry.

USER: That's ok, thank you for re-checking.

ASSISTANT: Thank you for opting us.