Dialog bahasa inggris question tag

A : The world is round, isn't it?
B : yes, it is. Everybody knows that.
A : Elephants have trunks, don't they?
B : Yes, they do.
A : Shakespeare didn't write Faust, did he?
B : No, he didn't. Marlowe did.
A : My girlfriend is pretty, isn't she?
B : why are you asking me this?
A : Dogs can't fly, can they?
B : arrgh!!
A : hehehe, sorry. I'm just practicing my question tags.