You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you now?

USER:  I want to attend a cultural exhibition at Seattle, WA-SEA, Can you help me with booking a flight ticket?

ASSISTANT: Sure, please share me your journey dates?

USER: Sure,My source is at San Francisco, CA-SFO, and my preferred dates are  from 03/20 to 03/22.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting. Sorry, there is no any flight available on your journey details.

USER: Ok, No issue. Thank you for your help.

ASSISTANT: May I know your name?

USER: Sure, I am Nicholas Davis.

ASSISTANT: Thanks for your name, have a nice day.