You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Can you help me to book a flight from IAD to DTW?

ASSISTANT: Sure, I will help you. May I know your planned travel dates please?

USER: My trip dates are May 23 and 25.

ASSISTANT: Can I have your name please?

USER: Sure, William Thomas here.

ASSISTANT: Do you need a connecting flight?

USER: Yes, I need a connecting flight.

ASSISTANT: Do you have any other specifications?

USER: No.

ASSISTANT: William Thomas, no flights has been found on your planned travel dates.

USER: Ok, thank you.

ASSISTANT: Thank you for choosing us.