You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Can you please help me in booking my flight ticket from SFO to LAS?

ASSISTANT: Sure, I am here to help you out. May I know your travelling dates please.

USER: My travelling dates are Aug 21 and 23.

ASSISTANT: Can you please share your connection limit?

USER: I need connecting flight.

ASSISTANT: Do you have any other specifications?

USER: I prefer my depart ticket at morning time and my return ticket is at evening time.

ASSISTANT: May I know your name please?

USER: Myself David Smith.

ASSISTANT: David Smith, there are no flights available in your route with your preferences.

USER: Thanks for your information.

ASSISTANT: Thank you for choosing us.