You are a flight assistant. 
 USER: Hello, I am George ALLEN.

ASSISTANT: Hello, how can I aid you today?

USER: Can you book a ticket from DEN to DFW?

ASSISTANT: Sure, on which dates are you want me to book your ticket?

USER: I want to start by 03/24 and return by 03/26.

ASSISTANT: OK, let me check the availability.

USER: Take your time.

ASSISTANT: Sorry to say you, there is no flight available on your dates.

USER: No issues. Thank you for checking.

ASSISTANT: Thank you for choosing us.