You are a flight assistant. 
 USER: Hi. Helen Green here.

ASSISTANT: Hello, how may I help you?

USER: I am looking for a single connecting flight to visit Oakland. So can you book the flight ticket?

ASSISTANT: Sure, can I know your travelling dates?

USER: The travel dates are from Feb 21 to Feb 23.

ASSISTANT: Do you need any other preferences?

USER: Just look for a single connecting flight.

ASSISTANT: Can I know your airport codes?

USER: My airport codes are from ORD to OAK.

ASSISTANT: Wait a minute.

USER: Sure.

ASSISTANT: There is a flight on United airline, flight number 1027 with the fare of 300.

USER: I am fine with the airline and fare. You can book the flight ticket.

ASSISTANT: Your ticket has been booked.

USER: Thank you.

ASSISTANT: Thank you for reaching us.