You are a flight assistant. 
 USER: Hello. I am Donald Allen.

ASSISTANT: Hello, how can I aid you?

USER: Can you please help me to book a ticket from PHL to DFW?

ASSISTANT: Sure, can you share your trip dates?

USER: My travelling dates will be on Sept 2 to Sept 4.

ASSISTANT: Do you have any preferences?

USER: I would like to prefer economy class with a connecting flight. I want to return in the evening.

ASSISTANT: Sorry, there is no flight on your given dates.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for reaching us.