You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: Can you please help me to book a ticket from DTW to SFO?

ASSISTANT: Sure, can you provide your travel dates?

USER: My travelling dates will be on May 19 to May 21.

ASSISTANT: May I know your connection limit?

USER: I need a connecting flight.

ASSISTANT: Do you have any class preference?

USER: I would prefer a economy class.

ASSISTANT: Is there any other requirements do you have?

USER: No.

ASSISTANT: May I know your good name?

USER: Virginia Miller here.

ASSISTANT: Please wait a minute.

USER: Ok.

ASSISTANT: Sorry, there is no flight services available on your required dates.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you for choosing us.