You are a flight assistant. 
 USER: Hi. I am Nancy White.

ASSISTANT: Hello, how may I best serve you now?

USER: I want to book a flight ticket on 01/15 and return on 01/17, so can you help me with booking please?

ASSISTANT: Sure, please share me your airport abbreviates?

USER:     Sure, my airport codes are Denver, CO-DEN and Washington, DC-IAD.

ASSISTANT: Do you need any lay over in between journey?

USER: Yes, I need a connecting flight.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry to inform that, there is a no connecting flight available on your journey dates.

USER: That's ok, thank you for the information.

ASSISTANT: Thanks for consulting us, have a nice day.