You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Christine King, want to travel from OAK to ORD.

ASSISTANT: May I know your trip dates?

USER: My travelling dates are from 05/17 to 05/19.

ASSISTANT: Sorry, there is no flight available.

USER: It's ok, thank you.

ASSISTANT: Welcome.