You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you at present?

USER: Can you please help me to book a flight from DEN to DTW?

ASSISTANT: Sure, can I know your good name please?

USER: I am Kevin Williams.

ASSISTANT:  When you are willing to travel?

USER: My travel dates are July 18 to 20.

ASSISTANT: Do you need direct flight or connecting flight?

USER: I prefer connecting flight.

ASSISTANT: Are there any other specifications?

USER: My depart time should be morning.

ASSISTANT: Sorry to say that, there are no flights available on the routes of your journey.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.