You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you help me to book a connecting flight from OAK to DFW?

ASSISTANT: Let me know your travelling dates.

USER: I want to fly on 13 Oct and return on 15 Oct.

ASSISTANT: Do you have any preference?

USER: I prefer to travel in business class.

ASSISTANT: Can I know your name?

USER: I am Melissa Gonzalez.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: Oh! that very sad to hear, thank you.

ASSISTANT: Thank you.