You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Can you help me to book a flight ticket from DFW to LGA?

ASSISTANT: Sure, may I know the travelling dates?

USER: My trip dates are 17 to 19 of Nov.

ASSISTANT: Do you have any connection limit?

USER: I need a connecting flight.

ASSISTANT: Is there any other requirements?

USER: I prefer to depart in the evening.

ASSISTANT: May I know your name?

USER: I am Thomas Walker.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, no flights found with your chosen dates.

USER: Oh! that very sad to hear, thank you.

ASSISTANT: Thank you for opting us.