You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I am Elizabeth Miller want to visit DCA, can you book a ticket from SFO?

ASSISTANT: May I know your travelling dates?

USER: Sure, my travelling dates will be 07/10 and 07/12.

ASSISTANT: Sorry, I could not find any flight with your travel dates.

USER: That's ok, thank you.

ASSISTANT: Thanks for choosing us.