I am sorry

某人刻苦学习英语，终有小成。一日上街不慎与一老外相撞，

>  忙说：I am sorry.

>  老外应道：I am sorry too.

>  某人听后又道：I am sorry three.

>  老外不解，问：What are you sorry for?

>  某人无奈，道：I am sorry five.