You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I serve you?

USER: I am Carol Hall. Please book a flight ticket from Denver, DEN to Phoenix, PHX.

ASSISTANT: Sure, We are here to assist you.

USER: Thank you.

ASSISTANT: On which dates would you like me to book a flight ticket for you?

USER: My travelling dates are from 12/13 to 12/15.

ASSISTANT: Do you need any connecting flight?

USER: No, I need a direct flight.

ASSISTANT: Let me check what flights are available for you.

USER: Sure.

ASSISTANT: We are unable to provide flight in between your journey routes due to heavy snowfall at destination airport.

USER: Ok, Not an issue. Thank you.

ASSISTANT: Thank you for choosing us.