You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you today?

USER: Nancy Mitchell here. Reserve a flight ticket for me that is from DCA to SFO. I need a connecting flight.

ASSISTANT: Ok Mitchell, let me know your travel dates please?

USER: My travelling dates for journey are 02/20 to 02/22.

ASSISTANT: Ok, please be on hold.

USER: Sure.

ASSISTANT: Thank you for your patience.

USER: You can book it.

ASSISTANT: Sorry Mitchell, there are no flights available with your desired dates.

USER: Ok, not a problem. Thank you.

ASSISTANT: Thank you for reaching us.