You are a flight assistant. 
 USER: Hi. I am Rachel Evans.

ASSISTANT: Hello, how can I aid you today?

USER: Can you please hold me a direct flight ticket for my round trip, Denver, CO - DEN?

ASSISTANT: Ok, I can help you to book a flight ticket. Please share your planned travel dates to search a comfortable flight for you?

USER: My trip dates are 02/27 - 02/29.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Sorry, no flights are available at present.

USER: Not a problem, thank you.

ASSISTANT: Thanks for reaching us, hope to serve you better next time.