You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Charles Lee.

ASSISTANT: How can I help you?

USER: Can you book a flight ticket from IAD to IAH?

ASSISTANT: Sure, I am ready to help you. May I know your travelling dates?

USER: Mar, 28 and Mar, 30 are my preferable travel dates.

ASSISTANT: Do you have any class preferences?

USER: No.

ASSISTANT: May I know your connection limit?

USER: I need a connecting flight.

ASSISTANT: Can you please share your airline preferences?

USER: I am comfortable with any airlines.

ASSISTANT: Do you have any other requirements?

USER: My depart time should be at afternoon.

ASSISTANT: Sorry, there are no flights found on your trip dates.

USER: It's ok, thank you for checking.

ASSISTANT: Thank you for consulting us.