how come you speak such good duckish? are you a deep cover agent of some kind? who do you work for? what is your mission? was it hard for you to leave your family behind and live your life in a lie, so you can play your role successfully for not being discovered as your life could be at stake? it must be hard for you, i know... i know it too well....... or should i just say "quaaack quack quack, quaaack-quack"?
So some plurals have different spelling and pronunciation not just added on sounds at the end. Seems a bit of a pain to remember that difference. I hope its something consistent word to word. Apparently bøker can also mean beech trees. In this context there would be no confusion but if it was something like de har mange bøker then its not easy to tell if its someone with many beech trees or many books aside from assumption of commonality.