contoh dialog expessing and responding to doubt?

Fighting ...
A : Will you give me your best fight, B?
B : Of course, definetely I'll beat you, A ..
A : Okay, well. But I doubt it
B : Let's prove it

A : hi B ! how are you ?
B : hi A ! i am fine, thanks
A : B, why my cat are gone this morning ?
B : i don't know, but i am sure he will returning home
A : i doubt about it
B : calm down, you is the owner of your cat, so he will return to you. did you know that cat is a loyal pet ?
A : sure, i know