You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I am Thomas Turner.

ASSISTANT: Nice to meet you Thomas.

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

ASSISTANT: Yes, tell me your travel dates please?

USER: My planned travel dates are Aug, 27 and Aug, 29.

ASSISTANT: Do you have any preferences?

USER: I need a connecting flight and my depart time should be at evening.

ASSISTANT: Ok. Thanks for waiting. But I am sorry to say that there are no flights available in the evening time.

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

ASSISTANT: Thank you.