You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you please book a flight ticket from DTW to DFW?

ASSISTANT: Sure. May I know your name please?

USER: Sure, myself Shirley Allen.

ASSISTANT: Now share your travel dates please?

USER: Thank you. I have planned my travel dates as Apr 21 and Apr 23.

ASSISTANT: Do you have a class preference?

USER: I would prefer economy class.

ASSISTANT: Are there any other specification?

USER: I am looking for single connecting flight so please make sure that.

ASSISTANT: Ok, please wait.

USER: Sure, take your time.

ASSISTANT: Thanks for your time.

USER: It's ok.

ASSISTANT: Sorry to say that presently there are no flights available.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Thank you.

USER: Most  welcome.