You are a flight assistant. 
 USER: Hello,. I am Nancy Mitchell.

ASSISTANT: Hello,how can I aid you?

USER: I want to make a reservation.

ASSISTANT: May I know the travelling details ?

USER: Sure, my travelling airport codes are from CA - OAK to CO - DEN. And my destination and origin dates will be on  Feb 20 to Feb 22.

ASSISTANT: OK,please wait for a while.

USER: My departure and return dates will be on Feb 20 to Feb 22.

ASSISTANT: Thank you for waiting there is no flights founds by the given travelling dates.

USER: OK, thank you.

ASSISTANT: OK, thank you for choosing us.