You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: Can you aid me to book my ticket from PHL to LAS?

ASSISTANT: Sure, I will help you. Please send your travelling dates.

USER: My travel dates are Mar 11 and Mar 13 respectively.

ASSISTANT: Do you have any preferences?

USER: Make sure that connecting limit is single.

ASSISTANT: May I know your name please?

USER: Thomas Walker here.

ASSISTANT: Sorry, there is no flight available with single connection.

USER: Ok. Thank you for the help.

ASSISTANT: You are welcome, have a nice day.