You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Can you avail me to book a flight from DFW to IAD?

ASSISTANT: Ok, may I know your planned dates for this journey?

USER: My planned journey dates are Dec 03 and 05.

ASSISTANT: Do you need a connecting flight?

USER: Yes, I need it.

ASSISTANT: Please mention your name.

USER: William Davis here.

ASSISTANT: Sorry to say, there are no flights available for your journey.

USER: Ok, thank you.

ASSISTANT: Thank you for choosing us. Have a nice day.