You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Sandra White.

ASSISTANT: How can I help you?

USER: I would like to visit the National Mall in DCA in this vacation, so can you help me booking flight on 11/27?

ASSISTANT: Sure, do you have any specifications?

USER: Make sure with connection limit 1.

ASSISTANT: Can you share your origin location with date?

USER: I am going to return my source airport DEN on 11/19.

ASSISTANT: Give me a minute.

USER: Ok, I will wait for your response.

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

USER: Oh! Sad to hear, thank you for your quick response.

ASSISTANT: Thank you for picking us.